U.S. patent application number 14/353537 was filed with the patent office on 2014-09-11 for power plant.
This patent application is currently assigned to HONDA MOTOR CO., LTD.. The applicant listed for this patent is HONDA MOTOR CO., LTD.. Invention is credited to Kenji Honda.
Application Number | 20140256490 14/353537 |
Document ID | / |
Family ID | 48191983 |
Filed Date | 2014-09-11 |
United States Patent
Application |
20140256490 |
Kind Code |
A1 |
Honda; Kenji |
September 11, 2014 |
POWER PLANT
Abstract
A power plant capable of suppressing loss, and attaining
downsizing and enhancement of mountability of the power plant. In
the power plant T, the rotational speeds of third to first sun
gears S3 to S1 and a carrier member 111 are in a collinear
relationship with each other, and are sequentially aligned in the
mentioned order in a collinear chart indicating the relationship
between the rotational speeds. Further, the third sun gear S3 and
the carrier member 111 are connected to first and second torque
generators 113 and 114 capable of generating positive torque and
negative torque, respectively, and the second and first sun gears
S2 and S1 are connected to one and the other of two rotating
shafts, respectively.
Inventors: |
Honda; Kenji; (Wako-shi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HONDA MOTOR CO., LTD. |
Tokyo |
|
JP |
|
|
Assignee: |
HONDA MOTOR CO., LTD.
Tokyo
JP
HONDA MOTOR CO., LTD.
Tokyo
JP
|
Family ID: |
48191983 |
Appl. No.: |
14/353537 |
Filed: |
October 29, 2012 |
PCT Filed: |
October 29, 2012 |
PCT NO: |
PCT/JP2012/077884 |
371 Date: |
April 23, 2014 |
Current U.S.
Class: |
475/5 ;
180/65.22; 903/902 |
Current CPC
Class: |
B60K 1/02 20130101; Y10S
903/902 20130101; Y02T 10/6265 20130101; F16H 2048/364 20130101;
B60K 6/547 20130101; B60K 6/52 20130101; F16H 48/36 20130101; Y02T
10/62 20130101 |
Class at
Publication: |
475/5 ;
180/65.22; 903/902 |
International
Class: |
B60K 6/547 20060101
B60K006/547 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 2, 2011 |
JP |
2011-241371 |
Mar 28, 2012 |
JP |
2012-074211 |
Claims
1. A power plant that drives two rotating shafts configured to be
differentially rotatable with each other in order to move a moving
apparatus, comprising: a carrier member that is rotatable; a triple
pinion gear that is formed by a first pinion gear, a second pinion
gear, and a third pinion gear, which are integrally formed with
each other, and is rotatably supported by said carrier member; a
first sun gear that is rotatable and is in mesh with said first
pinion gear; a second sun gear that is rotatable and is in mesh
with said second pinion gear; a third sun gear that is rotatable
and is in mesh with said third pinion gear, wherein said triple
pinion gear and said first to third sun gears are configured such
that when said triple pinion gear is rotating in a state in which
said carrier member is fixed, a rotational speed of said second sun
gear becomes higher than a rotational speed of said first sun gear,
and a rotational speed of said third sun gear becomes higher than
the rotational speed of said second sun gear, the power plant
further comprising: a first torque generator that is capable of
generating positive torque and negative torque; and a second torque
generator that is capable of generating positive torque and
negative torque, wherein said third sun gear is connected to said
first torque generator, said second sun gear is connected to one of
the two rotating shafts, said first sun gear is connected to the
other of the two rotating shafts, and said carrier member is
connected to said second torque generator.
2. The power plant according to claim 1, further comprising a
differential limiting mechanism that is connected to said third sun
gear and said carrier member, for limiting differential rotation
between the two rotating shafts by connecting and disconnecting
between said third sun gear and said carrier member.
3. The power plant according to claim 2, further comprising: a
first power transmission mechanism that is provided in a power
transmission path between said third sun gear and said differential
limiting mechanism, for transmitting reaction force torque of said
differential limiting mechanism, generated by connection between
said third sun gear and said carrier member by said differential
limiting mechanism, to said third sun gear, in an increased state;
and a second power transmission mechanism that is provided in a
power transmission path between said carrier member and said
differential limiting mechanism, for transmitting reaction force
torque of said differential limiting mechanism, generated by
connection between said third sun gear and said carrier member by
said differential limiting mechanism, to said carrier member, in an
increased state.
4. The power plant according to claim 1, further comprising: a
differential gear that includes a first rotating body, a second
rotating body, and a third rotating body, which are differentially
rotatable with each other; and a torque generator that is capable
of generating positive torque, and is provided separately from said
first and second torque generators, and wherein said first rotating
body is connected to said second sun gear, said second rotating
body is provided in a power transmission path between said first
sun gear and the other of the two rotating shafts, and said third
rotating body is connected to said torque generator.
5. The power plant according to claim 1, wherein said first and
second torque generators are rotating electric machines.
6. A power plant that drives two rotating shafts configured to be
differentially rotatable with each other in order to move a moving
apparatus, comprising: a gear unit that includes a first element, a
second element, a third element, and a fourth element, between
which motive power can be transmitted, and is configured such that
rotational speeds of said first to fourth elements are in a
predetermined collinear relationship in which the rotational speeds
are located on the same straight line in a collinear chart, and
when said second to fourth elements are caused to rotate in a state
of said first element being fixed, said second to fourth elements
rotate in the same direction, and the rotational speed of said
fourth element becomes higher than the rotational speeds of said
second and third elements; a first torque generator that is capable
of generating positive torque and negative torque; and a second
torque generator that is capable of generating positive torque and
negative torque, wherein said first element is connected to said
first torque generator, said second element is connected to one of
the two rotating shafts, said third element is connected to the
other of the two rotating shafts, and said fourth element is
connected to said second torque generator, the power plant further
comprising a differential limiting mechanism that is connected to
said first and fourth elements, for limiting differential rotation
between the two rotating shafts by connecting and disconnecting
between said first element and said fourth element.
7. The power plant according to claim 6, further comprising: a
first power transmission mechanism that is provided in a power
transmission path between said first element and said differential
limiting mechanism, for transmitting reaction force torque of said
differential limiting mechanism, generated by connection between
said first element and said fourth element by said differential
limiting mechanism, to said first element, in an increased state;
and a second power transmission mechanism that is provided in a
power transmission path between said fourth element and said
differential limiting mechanism, for transmitting reaction force
torque of said differential limiting mechanism, generated by
connection between said first element and said fourth element by
said differential limiting mechanism, to said fourth element, in an
increased state.
8. The power plant according to claim 6, further comprising: a
differential gear that includes a fifth element, a sixth element,
and a seventh element, which are differentially rotatable with each
other; and a torque generator that is capable of generating
positive torque, and is provided separately from said first and
second torque generators, and wherein said fifth element is
connected to said second element, said sixth element is provided in
a power transmission path between said third element and the other
of the two rotating shafts, and said seventh element is connected
to said torque generator.
9. The power plant according to claim 6, wherein said first and
second torque generators are rotating electric machines.
10. The power plant according to claim 2, further comprising: a
differential gear that includes a first rotating body, a second
rotating body, and a third rotating body, which are differentially
rotatable with each other; and a torque generator that is capable
of generating positive torque, and is provided separately from said
first and second torque generators, and wherein said first rotating
body is connected to said second sun gear, said second rotating
body is provided in a power transmission path between said first
sun gear and the other of the two rotating shafts, and said third
rotating body is connected to said torque generator.
11. The power plant according to claim 3, further comprising: a
differential gear that includes a first rotating body, a second
rotating body, and a third rotating body, which are differentially
rotatable with each other; and a torque generator that is capable
of generating positive torque, and is provided separately from said
first and second torque generators, and wherein said first rotating
body is connected to said second sun gear, said second rotating
body is provided in a power transmission path between said first
sun gear and the other of the two rotating shafts, and said third
rotating body is connected to said torque generator.
12. The power plant according to claim 2, wherein said first and
second torque generators are rotating electric machines.
13. The power plant according to claim 3, wherein said first and
second torque generators are rotating electric machines.
14. The power plant according to claim 4, wherein said first and
second torque generators are rotating electric machines.
15. The power plant according to claim 7, further comprising: a
differential gear that includes a fifth element, a sixth element,
and a seventh element, which are differentially rotatable with each
other; and a torque generator that is capable of generating
positive torque, and is provided separately from said first and
second torque generators, and wherein said fifth element is
connected to said second element, said sixth element is provided in
a power transmission path between said third element and the other
of the two rotating shafts, and said seventh element is connected
to said torque generator.
16. The power plant according to claim 7, wherein said first and
second torque generators are rotating electric machines.
17. The power plant according to claim 8, wherein said first and
second torque generators are rotating electric machines.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a power plant that drives
two rotating shafts configured to be differentially rotatable with
each other in order to move a moving apparatus.
BACKGROUND ART
[0002] Conventionally, as a power plant of this kind, one disclosed
in PTL 1 is known. This conventional power plant is applied to a
four-wheel vehicle, and includes an internal combustion engine as a
motive power source, a differential gear for distributing torque of
the engine to left and right output shafts, a rotatable carrier
member, a triple pinion gear rotatably supported by the carrier
member, and hydraulic speed-increasing and speed-reducing clutches.
The left and right output shafts are connected to left and right
drive wheels, respectively. Further, the triple pinion gear
comprises a first pinion gear, a second pinion gear, and a third
pinion gear, which have pitch circles different from each other,
and these first to three pinion gears are integrally formed with
each other. The first pinion gear is in mesh with a first sun gear
integrally formed with the right output shaft, and the second
pinion gear is in mesh with a second sun gear integrally formed
with the left output shaft. Further, the third pinion gear is in
mesh with a rotatable third sun gear. Furthermore, the third sun
gear and an immovable casing are connected to and disconnected from
each other by the speed-increasing clutch, and the carrier member
and the casing are connected to and disconnected from each other by
the speed-reducing clutch.
[0003] In the conventional power plant constructed as above, during
straight forward traveling thereof, the third sun gear and the
casing are disconnected from each other by disengagement of the
speed-increasing clutch, and the carrier member and the casing are
disconnected from each other by disengagement of the speed-reducing
clutch. Further, torque of the engine is distributed to the left
and right output shafts via the differential gear. Accordingly, the
carrier member, the third sun gear, and the speed-increasing and
speed-reducing clutches idly rotate along with transmission of
rotation from the engine. Further, during the left or right turning
of the vehicle, by controlling the engagement forces of the
speed-increasing and speed-reducing clutches, the distribution of
torque to the left and right output shafts is controlled.
Specifically, during the right turning of the vehicle, the third
sun gear and the casing are disconnected from each other by
disengagement of the speed-increasing clutch, and the carrier
member and the casing are connected to each other by engaging the
speed-reducing clutch, whereby the carrier member is decelerated.
This causes part of torque of the right output shaft to be
transmitted to the left output shaft via the first sun gear, the
first pinion gear, the second pinion gear, and the second sun gear,
so that torque distributed to the left output shaft is increased
with respect to the right output shaft. In this case, by
controlling the degree of the engagement of the speed-reducing
clutch, the torque distributed to the left output shaft is
controlled.
[0004] On the other hand, during the left turning of the vehicle,
the carrier member and the casing are disconnected from each other
by disengagement of the speed-reducing clutch, and the third sun
gear and the casing are connected to each other by engagement of
the speed-increasing clutch, whereby the carrier member is
accelerated. This causes part of torque of the left output shaft to
be transmitted to the right output shaft via the second sun gear,
the second pinion gear, the first pinion gear, and the first sun
gear, so that torque distributed to the right output shaft is
increased with respect to the left output shaft. In this case, by
controlling the degree of the engagement of the speed-increasing
clutch, the torque distributed to the right output shaft is
controlled.
CITATION LIST
[0005] [Patent Literature 1] [0006] [PTL 1] Publication of Japanese
Patent No. 3104157
SUMMARY OF INVENTION
Technical Problem
[0007] As described above, in the conventional power plant, the
speed-increasing and speed-reducing clutches are used to control
distribution of torque to the left and right output shafts, and
these speed-increasing and speed-reducing clutches idly rotate as
rotation from the engine is transmitted. Therefore, when wet
friction clutches are used as the speed-increasing and
speed-reducing clutches, large dragging losses are caused by shear
resistance due to the viscosity of lubricating oil therefor.
[0008] Further, when a hydraulic pump which uses the engine as a
motive power source is used for supplying oil pressure to the
hydraulic speed-increasing and speed-reducing clutches, the
hydraulic pump is always driven during operation of the engine
irrespective of the distribution control of torque to the left and
right output shafts, and hence torque of the engine is wastefully
consumed. Furthermore, a spool valve, a solenoid, a strainer, and
so forth are required for driving the speed-increasing and
speed-reducing clutches, which causes an increase in the size of
the power plant and degradation of mountability thereof.
[0009] The present invention has been made to provide a solution to
the above-described problems, and an object thereof is to provide a
power plant which is capable of suppressing loss and attaining size
reduction and enhancement of mountability thereof.
Solution to Problem
[0010] To attain the above object, the invention according to claim
1 is a power plant 1, 1A to 1E (power transmission system T) that,
in order to move a moving apparatus (vehicle VFR, vehicle VAW in
embodiments (the same applies hereinafter in this section)), drives
two rotating shafts (left and right output shafts SRL and SRR, left
and right output shafts SFL and SFR) configured to be
differentially rotatable with each other, comprising a carrier
member 13, 111 that is rotatable, a triple pinion gear 14, 112 that
is formed by a first pinion gear P1, a second pinion gear P2, and a
third pinion gear P3, which are integrally formed with each other,
and is rotatably supported by the carrier member 13, 111, a first
sun gear S1 that is rotatable and is in mesh with the first pinion
gear P1, a second sun gear S2 that is rotatable and is in mesh with
the second pinion gear P2, a third sun gear S3 that is rotatable
and is in mesh with the third pinion gear P3, wherein the triple
pinion gear 14, 112 and the first to third sun gears S1 to S3 are
configured such that when the triple pinion gear 14, 112 is
rotating in a state in which the carrier member 13, 111 is fixed, a
rotational speed of the second sun gear S2 becomes higher than a
rotational speed of the first sun gear S1, and a rotational speed
of the third sun gear S3 becomes higher than the rotational speed
of the second sun gear S2, the power plant further comprising a
first torque generator (first rotating electric machine 11, first
motor 113) that is capable of generating positive torque and
negative torque, and a second torque generator (second rotating
electric machine 12, second motor 114) that is capable of
generating positive torque and negative torque, wherein the third
sun gear S3 is connected to the first torque generator, the second
sun gear S2 is connected to one (left output shaft SRL, SFL) of the
two rotating shafts, the first sun gear S1 is connected to the
other (right output shaft SRR, SFR) of the two rotating shafts, and
the carrier member 13, 111 is connected to the second torque
generator, and is connected to the third sun gear S3 and the
carrier member 13, 111.
[0011] With this arrangement, the triple pinion gear is rotatably
supported by the rotatable carrier member and the rotatable first
to third sun gears are in mesh with the first to third pinion
gears, which form the triple pinion gear and are integrally formed
with each other, respectively. Further, the triple pinion gear and
the first to third sun gears are configured such that when the
triple pinion gear is rotating in the state in which the carrier
member is fixed, the rotational speed of the second sun gear
becomes higher than the rotational speed of the first sun gear, and
the rotational speed of the third sun gear becomes higher than the
rotational speed of the second sun gear. With this configuration,
four rotary elements the rotational speeds of which are in a
collinear relationship with each other is formed by the third to
first sun gears and the carrier member. Here, the term "collinear
relationship" refers to a relationship in which the rotational
speeds of them are located on the same straight line in a collinear
chart. Further, from the above-described relationship between the
rotational speeds of the first to third sun gears, the third sun
gear, the second sun gear, the first sun gear, and the carrier
member are aligned in the mentioned order in this collinear
chart.
[0012] Furthermore, the third sun gear is connected to the first
torque generator, the second and first sun gears are connected to
one of the two rotating shafts (hereinafter referred to as the "one
rotating shaft"), and the other of the two rotating shafts
(hereinafter referred to as the "other rotating shaft"),
respectively, and the carrier member is connected to the second
torque generator. From the above, it is possible to transmit the
positive torque and the negative torque generated by the first and
second torque generators (load torque) to the two rotating shafts
via the third to first sun gears and the carrier member, to
properly drive the rotating shafts. In this case, the rotational
speeds of the third to first sun gears and the carrier member are
in the collinear relationship with each other as described above,
so that by controlling the positive torque and the negative torque
generated by the first and second torque generators, it is possible
to properly control torque distributed to the two rotating shafts.
Note that the phrase "negative torque generated by the first and
second torque generators" refers to torque which acts as load on
the third sun gear and the carrier member connected to the first
and second torque generators, respectively.
[0013] Further, differently from the conventional case described
hereinabove, to control the torque distributed to the two rotating
shafts, not the speed-increasing and speed-reducing clutches formed
by wet friction clutches but the first and second torque generators
are used, and no large dragging losses occur, and therefore loss
can be suppressed. In addition to this, it is possible to dispense
with a hydraulic pump for supplying oil pressure to the
speed-increasing and speed-reducing clutches. Furthermore, it is
also possible to dispense with a spool valve, a solenoid, a
strainer, and so forth, for driving the two clutches, and it is
possible to downsize the power plant and enhance the mountability
thereof accordingly.
[0014] The invention according to claim 2 is the power plant 1, 1A
to 1E according to claim 1, further comprising a differential
limiting mechanism 16, 41 for limiting differential rotation
between the two rotating shafts by connecting and disconnecting
between the third sun gear S3 and the carrier member 13.
[0015] With this arrangement, out of the four rotary elements
consisting of the third to first sun gears and the carrier member,
rotary elements positioned at opposite ends of the straight line in
the collinear chart, that is, the third sun gear and the carrier
member are connected to and disconnected from each other by the
differential limiting mechanism. Since the rotational speeds of the
third to first sun gears and the carrier member are in the
collinear relationship with each other, the third to first sun
gears and the carrier member are caused to rotate in unison with
each other by the connection between the third sun gear and the
carrier member by the differential limiting mechanism, and hence it
is possible to limit differential rotation between the one rotating
shaft having the second sun gear connected thereto and the other
rotating shaft having the first sun gear connected thereto, thereby
making it possible to enhance stability of the behavior of the
moving apparatus. In this case, since it is only required to simply
connect the differential limiting mechanism, it is possible to
easily limit the differential rotation between the two rotating
shafts, and obtain high responsiveness of the differential limiting
mechanism.
[0016] Further, FIG. 23 is a collinear chart illustrating an
example of a rotational speed relationship and a torque balance
relationship between the various elements, obtained assuming that
the third sun gear and the carrier member are connected by the
differential limiting mechanism, in a case where the rotational
speed of the other rotating shaft is higher than the rotational
speed of the one rotating shaft. In FIG. 23, the distance from a
horizontal line indicative of 0 to a white circle shown on each
vertical line corresponds to the rotational speed of each of the
rotary elements. The same applies to other collinear charts,
referred to hereinafter. In FIG. 23, RC1 represents reaction force
torque acting on the third sun gear from the differential limiting
mechanism along with the connection of the differential limiting
mechanism, and RLC1 and RRC1 represent reaction force torques
acting on the one rotating shaft and the other rotating shaft,
respectively, as the reaction force torque RC1 acts on the third
sun gear. Further, RC2 represents reaction force torque acting on
the carrier member from the differential limiting mechanism along
with the connection of the differential limiting mechanism, and
RLC2 and RRC2 represent reaction force torques acting on the one
rotating shaft and the other rotating shaft, respectively, as the
reaction force torque RC2 acts on the carrier member.
[0017] In this case, torque transmitted to the one rotating shaft
along with the connection of the differential limiting mechanism is
expressed by RLC1+RLC2=RC1.times.(X+1)+RC2.times.Y, and torque
transmitted to the other rotating shaft along with the connection
is expressed by -{RRC1+RRC2}=-{RC1.times.X+RC2.times.(Y+1)}. As
described above, the torque transmitted to the one rotating shaft
having a lower rotational speed increases, and braking torque acts
on the other rotating shaft having a higher rotational speed,
whereby the differential rotation between the two rotating shafts
is reduced and limited. Further, as is apparent from the connection
between the third sun gear and the carrier member, the reaction
force torques RC1 and RC2, which act on the third sun gear and the
carrier member from the differential limiting mechanism,
respectively, are not only opposite in direction but also equal in
magnitude to each other.
[0018] From the above, the sum total of the differential limiting
torques, which act on the respective two rotating shafts by the
connection of the differential limiting mechanism such that the
differential rotation between the rotating shafts is limited
(hereinafter referred to as "total differential limiting torque")
is expressed by
RC1.times.(X+1)+RC1.times.Y+{RC1.times.X+RC1.times.(Y+1)}=2.times.RC1.tim-
es.(X+Y+1) when RC1 is used as a representative of the reaction
force torques RC1 and RC2.
[0019] Further, FIG. 24 is a collinear chart illustrating an
example of a rotational speed relationship and a torque balance
relationship between the various rotary elements, obtained
assuming, differently from the above-described invention, that out
of the above-described four rotary elements, the second sun gear
connected to the one rotating shaft and the first sun gear
connected to the other rotating shaft are connected by the
differential limiting mechanism, in the case in which the
rotational speed of the other rotating shaft is higher than the
rotational speed of the one rotating shaft. In FIG. 24, RC1 and RC2
represent reaction force torques acting on the respective second
and first sun gears from the differential limiting mechanism along
with connection of the differential limiting mechanism.
[0020] In this case, torque transmitted to the one rotating shaft
and torque transmitted to the other rotating shaft along with the
connection of the differential limiting mechanism are represented
by RC1 and -RC2, respectively. As described above, the torque
transmitted to the one rotating shaft having a lower rotational
speed increases, and braking torque acts on the other rotating
shaft having a higher rotational speed, so that the differential
rotation between the two rotating shafts is limited. Further, as is
apparent from the connection between the first and second sun
gears, the reaction force torques RC1 and RC2, which act on the
second and first sun gears from the differential limiting
mechanism, respectively, are not only opposite in direction but
also equal in magnitude to each other.
[0021] From the above, total differential limiting torque acting by
the connection of the differential limiting mechanism between the
second and first sun gears is expressed by RC1+RC1=2.times.RC1 when
RC1 is used as a representative of the reaction force torques RC1
and RC2. On the other hand, as described hereinabove, the total
differential limiting torque according to the present invention
(FIG. 23) becomes larger than the case where the connection between
the second and first sun gears is effected (FIG. 24), as is
apparent from the expression of 2.times.RC1.times.(X+Y+1).
[0022] Further, FIG. 25 is a collinear chart illustrating an
example of a rotational speed relationship and a torque balance
relationship between the various elements, obtained assuming,
differently from the above-described invention, that out of the
four rotary elements, the third sun gear and the first sun gear are
connected by the differential limiting mechanism, in the case where
the rotational speed of the other rotating shaft is higher than the
rotational speed of the one rotating shaft. In FIG. 25, RC1
represents reaction force torque acting on the third sun gear from
the differential limiting mechanism along with the connection of
the differential limiting mechanism, and RLC1 and RRC1 represent
reaction force torques acting on the one rotating shaft and the
other rotating shaft, respectively, as the reaction force torque
RC1 acts on the third sun gear. Further, RC2 represents reaction
force torque acting on the other rotating shaft via the first sun
gear from the differential limiting mechanism along with the
connection of the differential limiting mechanism, and RLC2 and
RSC2 represent reaction force torques acting on the one rotating
shaft and the third sun gear, respectively, as the reaction force
torque RC2 acts on the first sun gear.
[0023] In this case, torque transmitted to the one rotating shaft
along with the connection of the differential limiting mechanism is
expressed by RLC1-RLC2=RC1.times.(X+1)-RC2.times.(X+1)/X, and
torque transmitted to the other rotating shaft along with the
connection is expressed by -(RC2+RRC1)=-(RC2+RC1.times.X). As
described above, the torque transmitted to the one rotating shaft
having a lower rotational speed increases, and braking torque acts
on the other rotating shaft having a higher rotational speed, so
that the differential rotation between the two rotating shafts is
limited. Further, as is apparent from the connection between the
third sun gear and the first sun gear, the reaction force torques
RC1 and RC2, which act on the third sun gear and the first sun gear
from the differential limiting mechanism, respectively, are not
only opposite in direction but also equal in magnitude to each
other.
[0024] From the above, total differential limiting torque acting on
the two rotating shafts by the connection of the differential
limiting mechanism between the third and first sun gears is
expressed by
RC1.times.(X+1)-RC1.times.(X+1)/X+(RC1+RC1.times.X)=2.times.RC1.times.{X+-
1-(X+1)/(2.times.X)} when RC1 is used as a representative of the
reaction force torques RC1 and RC2. On the other hand, the total
differential limiting torque according to the present invention
(FIG. 23) becomes larger than the case where the third and first
sun gears are connected by the differential limiting mechanism
(FIG. 25), as is apparent from the expression of
2.times.RC1.times.(X+Y+1). The same applies to a case where two
rotary elements according to a combination other than the
above-described combination of two of the four rotary elements (the
third to first sun gears and the carrier member) are connected by
the differential limiting mechanism. Further, although FIGS. 23 to
25 are examples of the case in which the rotational speed of the
other rotating shaft is higher than the rotational speed of the one
rotating shaft, inversely to the above, also when the rotational
speed of the one rotating shaft is higher than the rotational speed
of the other rotating shaft, the total differential limiting torque
according to the present invention becomes larger.
[0025] As described above, by connecting, the third sun gear and
the carrier member of the four rotary elements, as rotary elements
positioned at opposite ends of the straight line in the collinear
chart, to each other, it is possible to obtain the largest total
differential limiting torque. This makes it possible to reduce
reaction force torque which is required of the differential
limiting mechanism to limit the differential rotation between the
two rotating shafts, and hence it is possible to downsize the
differential limiting mechanism, thereby making it possible to
further downsize the power plant and enhance the mountability
thereof.
[0026] Further, according to the present invention, to form four
rotary elements the rotational speeds of which are in the collinear
relationship with each other, a gear unit comprising the triple
pinion gear, the first to third sun gears, and the carrier member
is used. Therefore, compared with e.g. a case where a combination
of two planetary gear units of a single pinion type is used to form
the four rotary elements, it is possible to reduce the number of
component parts, and reduce the radial size of the gear unit since
the gear unit includes no ring gear.
[0027] The invention according to claim 3 is the power plant 1A, 1D
according to claim 2, further comprising a first power transmission
mechanism (gear 51, gear 52) that is provided in a power
transmission path between the third sun gear S3 and the
differential limiting mechanism 41, for transmitting reaction force
torque of the differential limiting mechanism 41, generated by
connection between the third sun gear S3 and the carrier member 14
by the differential limiting mechanism 41, to the third sun gear
S3, in an increased state, and a second power transmission
mechanism (gear 53, gear 54) that is provided in a power
transmission path between the carrier member 13 and the
differential limiting mechanism 41, for transmitting reaction force
torque of the differential limiting mechanism 41, generated by
connection between the third sun gear S3 and the carrier member 13
by the differential limiting mechanism 41, to the carrier member
13, in an increased state.
[0028] As is apparent from the description given of the invention
according to claim 2 with reference to FIG. 23, as the reaction
force torque of the differential limiting mechanism, generated by
the connection between the third sun gear and the carrier member by
the differential limiting mechanism is larger, the above-described
total differential limiting torque (torque that limits the
differential rotation between the two rotating shafts) becomes
larger. With the above-described arrangement, the reaction force
torque of the differential limiting mechanism is transmitted to the
third sun gear by the first power transmission mechanism in an
increased state, and is transmitted to the carrier member by the
second power transmission mechanism in an increased state.
Therefore, the total differential limiting torque can be increased,
and hence it is possible to further reduce the reaction force
torque which is required of the differential limiting mechanism to
limit the differential rotation between the two rotating shafts,
whereby it is possible to further downsize the differential
limiting mechanism. In this case, for example, when relatively
small-sized mechanisms, such as gears, are employed as the first
and second power transmission mechanisms, a space necessary for
arranging both the mechanisms is smaller than a space reduced by
downsizing the above-described differential limiting mechanism.
Therefore, by downsizing the differential limiting mechanism, it is
possible to further downsize the power plant and enhance the
mountability thereof.
[0029] The invention according to claim 4 is the power plant 1C to
1E (power transmission system T) according to any one of claims 1
to 3, further comprising a differential gear D that includes a
first rotating body (sun gear SD), a second rotating body (carrier
CD), and a third rotating body (ring gear RRD), which are
differentially rotatable with each other, and a torque generator
(engine 3) that is capable of generating positive torque, and is
provided separately from the first and second torque generators,
and wherein the first rotating body is connected to the second sun
gear S2, the second rotating body is provided in a power
transmission path between the first sun gear S1 and the other of
the two rotating shafts, and the third rotating body is connected
to the torque generator.
[0030] With this arrangement, the first to third rotating bodies of
the differential gear are configured to be differentially rotatable
with each other. Further, the first rotating body is connected to
the above-described second sun gear, and is connected to the one
rotating shaft via the second sun gear. The second rotating body is
provided in the power transmission path between the first sun gear
and the other rotating shaft, and the third rotating body is
connected to the torque generator. Further, this torque generator
is provided separately from the first and second torque generators.
From the above, in addition to the positive torque from the first
and second torque generators, the positive torque from the torque
generator is transmitted to the two rotating shafts, and hence it
is possible to reduce torque required of the first and second
torque generators, thereby making it possible to downsize the
torque generators.
[0031] The invention according to claim 5 is the power plant 1, 1A
to 1E (power transmission system T) according to any one of claims
1 to 4, wherein the first and second torque generators are rotating
electric machines.
[0032] With this arrangement, since general rotating electric
machines are used as the first and second torque generators, it is
possible to construct the power plant easily and more inexpensively
without using a special device. Further, in the case where
distribution of torque to the two rotating shafts is controlled as
described above, when negative torque is generated by the first and
second torque generators, it is possible to convert motive power to
electric power using the rotating electric machines. Therefore, for
example, when the power plant is applied to a vehicle, by supplying
the electric power obtained by the conversion to a vehicle
accessory, it is possible to reduce the operating load and
operating frequency of a generator for charging the power source of
the accessory.
[0033] To attain the above object, the invention according to claim
6 is a power plant 1, 1A to 1E that, in order to move a moving
apparatus (vehicle VFR, vehicle VAW in embodiments (the same
applies hereinafter in this section)), drives two rotating shafts
(left and right output shafts SRL and SRR, left and right output
shafts SFL and SFR) configured to be differentially rotatable with
each other comprising a gear unit GS that includes a first element
(third sun gear S3), a second element (second sun gear S2), a third
element (first sun gear S1), and a fourth element (carrier member
13), between which motive power can be transmitted, and is
configured such that rotational speeds of the first to fourth
elements are in a predetermined collinear relationship in which the
rotational speeds are located on the same straight line in a
collinear chart, and when the second to fourth elements are caused
to rotate in a state of the first element being fixed, the second
to fourth elements rotate in the same direction, and the rotational
speed of the fourth element becomes higher than the rotational
speeds of the second and third elements, a first torque generator
(first rotating electric machine 11) that is capable of generating
positive torque and negative torque, and a second torque generator
(second rotating electric machine 12) that is capable of generating
positive torque and negative torque, wherein the first element is
connected to the first torque generator, the second element is
connected to one (left output shaft SRL, SFL) of the two rotating
shafts, the third element is connected to the other (right output
shaft SRR, SFR) of the two rotating shafts, and the fourth element
is connected to the second torque generator, the power plant
further comprising a differential limiting mechanism 16, 41 that is
connected to the first and fourth elements, for limiting
differential rotation between the two rotating shafts by connecting
and disconnecting between the first element and the fourth
element.
[0034] With this arrangement, the first to fourth elements of the
gear unit are capable of transmitting motive power therebetween.
Further, the rotational speeds of the first to fourth elements are
in the predetermined collinear relationship in which the rotational
speeds are located on the same straight line in the collinear
chart, and when the second to fourth elements are caused to rotate
in the state in which the first element is fixed, the second to
fourth elements rotate in the same direction, and the rotational
speed of the fourth element becomes higher than the rotational
speeds of the second and third elements. Furthermore, the first
element is connected to the first torque generator, the second and
third elements are connected to one of the two rotating shafts
(hereinafter referred to as the "one rotating shaft"), and the
other of the two rotating shafts (hereinafter referred to as the
"other rotating shaft"), respectively, and the fourth element is
connected to the second torque generator.
[0035] From the above, it is possible to transmit the positive
torque and the negative torque generated by the first and second
torque generators, to the two rotating shafts via the gear unit, to
properly drive the rotating shafts. In this case, the rotational
speeds of the first to fourth elements are in the collinear
relationship with each other as described above, and hence by
controlling the positive torque and the negative torque generated
by the first and second torque generators, it is possible to
properly control torque distributed to the two rotating shafts.
Note that the phrase "negative torque generated by the first and
second torque generators" refers to torque which acts as load on
the first element and the fourth element connected to the first and
second torque generators, respectively.
[0036] Further, differently from the above-described conventional
case, to control the torque distributed to the two rotating shafts,
not the speed-increasing and speed-reducing clutches formed by wet
friction clutches but the first and second torque generators are
used, and therefore no large dragging losses occur, and hence loss
can be suppressed. In addition to this, it is possible to dispense
with a hydraulic pump for supplying oil pressure to the
speed-increasing and speed-reducing clutches. Furthermore, it is
also possible to dispense with a spool valve, a solenoid, a
strainer, and so forth, for driving the clutches, and attain
downsizing of the power plant and enhancement of the mountability
thereof accordingly.
[0037] With the above-described arrangement, the first element and
the fourth element of the first to fourth elements the rotational
speeds of which are in the collinear relationship are connected to
and disconnected from each other by the differential limiting
mechanism. This causes the first to fourth elements to rotate in
unison with each other, and hence it is possible to limit
differential rotation between the one rotating shaft having the
second element connected thereto and the other rotating shaft
having the third element connected thereto, whereby it is possible
to enhance the stability of the behavior of the moving apparatus.
In this case, it is only required to simply connect the
differential limiting mechanism, and hence it is possible to easily
limit the differential rotation between the two rotating shafts,
and obtain high responsiveness of the differential limiting
mechanism.
[0038] Further, as is apparent from the fact that the rotational
speeds of the first to fourth elements are in the collinear
relationship, and the fact that as described above, when the second
to fourth elements are caused to rotate in the state of the first
element being fixed, the second to fourth elements rotate in the
same direction, and the rotational speed of the fourth element
becomes higher than the rotational speeds of the second and third
elements, the first element and the fourth element are positioned
at opposite ends of the straight line in the collinear chart
showing the relationship between the rotational speeds of the first
to fourth elements. Therefore, by connecting the first element and
the fourth element by the differential limiting mechanism, it is
possible to maximize the total differential limiting torque (the
sum total of differential limiting torques which act on the
respective two rotating shafts such that the differential rotation
between the rotating shafts is limited). This makes it possible to
reduce reaction force torque required of the differential limiting
mechanism to limit the differential rotation between the two
rotating shafts, and hence it is possible to downsize the
differential limiting mechanism, thereby making it possible to
further downsize the power plant and enhance the mountability
thereof.
[0039] The invention according to claim 7 is the power plant 1A, 1D
according to claim 6, further comprising a first power transmission
mechanism (gear 51, gear 52) that is provided in a power
transmission path between the first element and the differential
limiting mechanism 41, for transmitting reaction force torque of
the differential limiting mechanism 41, generated by connection
between the first element and the fourth element by the
differential limiting mechanism 41, to the first element, in an
increased state, and a second power transmission mechanism (gear
53, gear 54) that is provided in a power transmission path between
the fourth element and the differential limiting mechanism 41, for
transmitting reaction force torque of the differential limiting
mechanism 41, generated by connection between the first element and
the fourth element by the differential limiting mechanism 41, to
the fourth element, in an increased state.
[0040] The invention according to the above-described claim 6 is
formed by expressing the third to first sun gears and the carrier
member of the invention according to claim 1, as the first to
fourth elements, in terms of more generic concepts, respectively.
Therefore, similarly to the invention according to claim 2, the
total differential limiting torque becomes larger as the reaction
force torque of the differential limiting mechanism, generated by
the connection between the first element and the fourth element by
the differential limiting mechanism is larger. With the
above-described arrangement, the above reaction force torque of the
differential limiting mechanism is transmitted to the first element
in an increased state by the first power transmission mechanism,
and is transmitted to the fourth element in an increased state by
the second power transmission mechanism. Therefore, since the total
differential limiting torque can be increased, it is possible to
further reduce the reaction force torque required of the
differential limiting mechanism to limit the differential rotation
between the two rotating shafts, whereby it is possible to further
downsize the differential limiting mechanism. In this case, for
example, when relatively small-sized mechanisms, such as gears, are
employed as the first and second power transmission mechanisms, a
space necessary for arranging both the mechanisms is smaller than a
space reduced by downsizing the above-described differential
limiting mechanism. Therefore, by downsizing the differential
limiting mechanism, it is possible to further downsize the power
plant and enhance the mountability thereof.
[0041] The invention according to claim 8 is the power plant 1C to
1E according to claim 6 or 7, further comprising a differential
gear D that includes a fifth element (sun gear SD), a sixth element
(carrier CD), and a seventh element (ring gear RD), which are
differentially rotatable with each other, and a torque generator
(engine 3) that is capable of generating positive torque, and is
provided separately from the first and second torque generators,
and wherein the fifth element is connected to the second element,
the sixth element is provided in a power transmission path between
the third element and the other of the two rotating shafts, and the
seventh element is connected to the torque generator.
[0042] With this arrangement, the fifth to seventh elements of the
differential gear are configured to be differentially rotatable
with each other. Further, the fifth element is connected to the
second element of the above-described gear unit, and is connected
to the one rotating shaft via the second element. The sixth element
is provided in the power transmission path between the third
element of the gear unit and the other rotating shaft, and the
seventh element is connected to the torque generator. Furthermore,
the torque generator is provided separately from the first and
second torque generators. From the above, in addition to the
positive torque from the first and second torque generators, the
positive torque from torque generator is transmitted to the two
rotating shaft, and hence it is possible to reduce torque required
of the first and second torque generators, thereby making it
possible to downsize the torque generators.
[0043] The invention according to claim 9 is the power plant 1, 1A
to 1E according to any one of claims 6 to 8, wherein the first and
second torque generators are rotating electric machines.
[0044] With this arrangement, general rotating electric machines
are used as the first and second torque generators, and hence it is
possible to construct the power plant easily and more inexpensively
without using a special device. Further, in the case where
distribution of torque to the two rotating shafts is controlled as
described above, when negative torque is generated by the first and
second torque generators, it is possible to convert motive power to
electric power using the rotating electric machines. Therefore, for
example, when the power plant is applied to a vehicle, by supplying
the electric power obtained by the conversion to a vehicle
accessory, it is possible to reduce the operating load and
operating frequency of a generator for charging the power source of
the accessory.
BRIEF DESCRIPTION OF THE DRAWINGS
[0045] FIG. 1 A diagram schematically showing a power transmission
system according to a first embodiment of the present invention
together with drive wheels of a vehicle to which the power
transmission system is applied.
[0046] FIG. 2 A block diagram showing an ECU etc.
[0047] FIG. 3 A view showing a state of transmission of torque in
the power transmission system during straight forward traveling of
the vehicle.
[0048] FIG. 4 A view showing a state of transmission of torque in
the power transmission system during left turning of the
vehicle.
[0049] FIG. 5 A view showing a state of transmission of torque in
the power transmission system during right turning of the
vehicle.
[0050] FIG. 6 A diagram schematically showing a power transmission
system according to a second embodiment of the present invention
together with drive wheels of a vehicle to which the power
transmission system is applied.
[0051] FIG. 7 A diagram schematically showing a power transmission
system according to a third embodiment of the present invention
together with drive wheels of a vehicle to which the power
transmission system is applied.
[0052] FIG. 8 A diagram schematically showing an FR type vehicle to
which the power transmission system according to the present
invention is applied.
[0053] FIG. 9 A diagram schematically showing an all-wheel drive
vehicle to which the power transmission system according to the
present invention is applied.
[0054] FIG. 10 A diagram schematically showing a power plant
according to a fourth embodiment of the present invention together
with rear wheels of a vehicle to which the power transmission
system is applied.
[0055] FIG. 11 A collinear chart showing a rotational speed
relationship and a torque balance relationship between various
types of rotary elements of the power plant shown in FIG. 10, in a
traveling state of the vehicle during straight forward traveling
thereof and at the same time other than deceleration traveling
thereof.
[0056] FIG. 12 A collinear chart showing the rotational speed
relationship and a torque balance relationship between various
types of rotary elements of the power plant shown in FIG. 10,
during straight forward traveling of the vehicle and at the same
time during deceleration traveling of the same.
[0057] FIG. 13 A collinear chart showing the rotational speed
relationship and a torque balance relationship between various
types of rotary elements of the power plant shown in FIG. 10,
during increasing control of a third yaw moment for right
turning.
[0058] FIG. 14 A collinear chart showing the rotational speed
relationship and a torque balance relationship between various
types of rotary elements of the power plant shown in FIG. 10,
during reducing control of the third yaw moment for right
turning.
[0059] FIG. 15 A diagram schematically showing a power plant
according to a fifth embodiment of the present invention together
with left and right rear wheels of a vehicle to which the power
plant is applied.
[0060] FIG. 16 A diagram schematically showing a power plant
according to a sixth embodiment of the present invention together
with left and right rear wheels of a vehicle to which the power
plant is applied.
[0061] FIG. 17 A diagram schematically showing a power plant
according to a seventh embodiment of the present invention together
with left and right front wheels of a vehicle to which the power
plant is applied.
[0062] FIG. 18 A collinear chart showing a rotational speed
relationship and a torque balance relationship between various
types of rotary elements of the power plant shown in FIG. 17,
during increasing control of the third yaw moment for right
turning.
[0063] FIG. 19 A diagram schematically showing a power plant
according to an eighth embodiment of the present invention together
with left and right front wheels of a vehicle to which the power
plant is applied.
[0064] FIG. 20 A diagram schematically showing a power plant
according to a ninth embodiment of the present invention together
with left and right front wheels of a vehicle to which the power
plant is applied.
[0065] FIG. 21 A diagram schematically showing an FR type vehicle
to which a power plant according to a first variation of the
seventh to ninth embodiments of the present invention is
applied.
[0066] FIG. 22 A diagram schematically showing an all-wheel drive
vehicle to which a power plant according to a second variation of
the seventh to ninth embodiments of the present invention is
applied.
[0067] FIG. 23 A collinear chart illustrating an example of
rotational speed relationship and a torque balance relationship
between various types of rotary elements in the present
invention.
[0068] FIG. 24 A collinear chart illustrating an example of a
rotational speed relationship and a torque balance relationship
between various types of rotary elements in a comparative example
compared with the present invention.
[0069] FIG. 25 A collinear chart illustrating an example of a
rotational speed relationship and a torque balance relationship
between various types of rotary elements in a comparative example
other than the comparative example shown in FIG. 24.
MODE FOR CARRYING OUT INVENTION
[0070] The invention will now be described in detail with reference
to drawings showing a preferred embodiment thereof. FIG. 1 shows an
internal combustion engine (hereinafter referred to as the
"engine") 3 which is installed on a four-wheel vehicle of FF
(front-engine front-drive) type (not shown). A power transmission
system T according to a first embodiment of the present invention
is connected to the engine 3 via a transmission 4, and transmits
torque of the engine 3 (hereinafter referred to as the "engine
torque") to a left front wheel WFL and a right front wheel WFR of
the vehicle.
[0071] The power transmission system T comprises a differential
gear D, a carrier member 111, triple pinion gears 112, a first
motor 113 and a second motor 114. The differential gear D, the
carrier member 111, the first motor 113, and the second motor 114
are arranged coaxially with each other. The differential gear D is
a planetary gear unit of a so-called double pinion type, and
comprises a sun gear SD, a ring gear RD disposed around an outer
periphery of the sun gear SD, a plurality of first pinion gears PD1
in mesh with the sun gear SD, a plurality of second pinion gears
PD2 in mesh with the first pinion gears PD1 and the ring gear RD,
and a carrier CD rotatably supporting the first and second pinion
gears PD1 and PD2.
[0072] Further, an externally toothed gear G is formed around an
outer periphery of the ring gear RD. This externally toothed gear G
is in mesh with a gear 4b integrally attached to an output shaft 4a
of the transmission 4. The carrier CD has a right end integrally
attached to a right output shaft SFR. The right output shaft SFR is
connected to the right front wheel WFR. Further, a hollow
cylindrical rotating shaft 115 is integrally attached to a left end
of the carrier CD, and is rotatably supported by a bearing (not
shown). Furthermore, the sun gear SD is integrally attached to a
left output shaft SFL. The left output shaft SFL is relatively
rotatably disposed inside the rotating shaft 115, and is connected
to the left front wheel WFL.
[0073] In the differential gear D configured as above, when the
engine torque is transmitted to the ring gear RD via the
transmission 4, the torque transmitted to the ring gear RD is
distributed to the sun gear SD and the carrier CD via the first and
second pinion gears PD1 and PD2 at a torque distribution ratio of
1:1. The torque distributed to the sun gear SD is transmitted to
the left front wheel WFL via the left output shaft SFL, and the
torque distributed to the carrier CD is transmitted to the right
front wheel WFR via the right output shaft SFR. Further, the left
and right output shafts SFL and SFR can be differentially rotated
with each other by the differential gear D.
[0074] The carrier member 111 comprises an annular plate-shaped
root portion 111a and four support shafts 111b (only two of which
are shown) for supporting the triple pinion gears 112. The carrier
member 111 is rotatably supported by a bearing (not shown), and is
disposed around the left output shaft SFL and the rotating shaft
115. Each support shaft 111b is integrally attached to the root
portion 111a, and extends from the root portion 111a in the axial
direction. Further, the four support shafts 111b are arranged at
equally-spaced intervals in the circumferential direction of the
root portion 111a.
[0075] The triple pinion gears 112 each comprise a first pinion
gear P1, a second pinion gear P2, and a third pinion gear P3, which
are integrally formed with each other. The number N of the triple
pinion gears 112 is 4 (only two of which are shown), and each
triple pinion gear 112 is rotatably supported on an associated one
of the support shafts 111b. The first to third pinion gears P1 to
P3 are arranged on the same axis parallel to the axis of the
carrier member 111 from the right side in the mentioned order. Note
that the number N of the triple pinion gears 112 and the number of
the support shafts 111b are not limited to 4 but they can be set as
desired.
[0076] The first to third pinion gears P1 to P3 have pitch circle
diameters different from each other, and the number of the gear
teeth of the first pinion gear P1 (hereinafter referred to as the
"first pinion tooth number") ZP1, the number of the gear teeth of
the second pinion gear P2 (hereinafter referred to as the "second
pinion tooth number") ZP2, and the number of the gear teeth of the
third pinion gear P3 (hereinafter referred to as the "third pinion
tooth number") ZP3 are set to values obtained by multiplying a
minimum tooth number M thereof by respective positive integers
(ones of M, 2M, 3M . . . ). Specifically, the first and second
pinion tooth numbers ZP1 and ZP2 are set to the minimum tooth
numbers M=17, and the third pinion tooth number ZP3 is set to
2M=34. This makes it possible to align the phases of the gear teeth
of the first to third pinion gears P1 to P3 with each other in the
circumferential direction. With this configuration, when the triple
pinion gears 112 are assembled, it is possible to dispense with
positioning of the triple pinion gears 112 in the circumferential
direction (the direction of rotation thereof), before bringing the
first to third pinion gears P1, P2, and P3 into mesh with a first
sun gear S1, a second sun gear S2 and a third sun gear S3, referred
to hereinafter, respectively, whereby it is possible to enhance
assemblability of the triple pinion gears 112.
[0077] Further, the first sun gear S1, the second sun gear S2, and
the third sun gear S3 are in mesh with the first to third pinion
gears P1, P2 and P3, respectively. The first sun gear S1 is
integrally attached to the rotating shaft 115, and the second sun
gear S2 is integrally attached to the left output shaft SFL. The
third sun gear S3 is integrally attached to a rotating shaft 116.
The rotating shaft 116 is rotatably supported by a bearing (not
shown), and the left output shaft SFL is relatively rotatably
disposed inside the rotating shaft 116.
[0078] Further, the number of the gear teeth of the first sun gear
S1 (hereinafter referred to as the "first sun gear tooth number")
ZS1, the number of the gear teeth of the second sun gear S2
(hereinafter referred to as the "second sun gear tooth number")
ZS2, and the number of the gear teeth of the third sun gear S3
(hereinafter referred to as the "third sun gear tooth number") ZS3
are set to values obtained by multiplying the number N of the
triple pinion gears 112 (4, in the present embodiment) by
respective positive integers (ones of N, 2N, 3N . . . ).
Specifically, the first and third sun gear tooth numbers ZS1 and
ZS3 are set to 8N=32, and the second sun gear tooth number ZS2 is
set to 7N=28. This makes it possible to cause the phases of the
gear teeth of the first to third sun gears S1 to S3 to coincide
with each other at a position where the first to third sun gears S1
to S3 are in mesh with the four triple pinion gears 112. With this
configuration, the phases of the gear teeth of the first to third
pinion gears P1 to P3 are not required to be made different from
each other, and hence it is possible to reduce the manufacturing
costs of the triple pinion gears 112.
[0079] Note that if the modules of the first pinion gear P1 and the
first sun gear S1 in mesh with each other are caused to coincide
with each other, the modules of the second pinion gear P2 and the
second sun gear S2 in mesh with each other are caused to coincide
with each other, and the modules of the third pinion gear P3 and
the third sun gear S3 in mesh with each other are caused to
coincide with each other, there is no need to cause all the modules
of the first to third pinion gears P1 to P3 and the first to third
sun gears S1 to S3 to coincide with each other.
[0080] The first motor 113 is an AC motor, and includes a first
stator 113a formed e.g. by a plurality of iron cores and coils, and
a first rotor 113b formed e.g. by a plurality of magnets. The first
stator 113a is fixed to an immovable casing CA. The first rotor
113b is disposed in a manner opposed to the first stator 113a, and
is integrally attached to the above-mentioned rotating shaft 116
such that it is rotatable together with the rotating shaft 116 and
the third sun gear S3. In the first motor 113, when electric power
(electric energy) is supplied to the first stator 113a, the
supplied electric power is converted to motive power (rotational
energy), and is output to the first rotor 113b. Further, when the
motive power (rotational energy) is input to the first rotor 113b,
this motive power is converted to electric power (electric energy)
(electric power generation), and is output to the first stator
113a.
[0081] Further, the first stator 113a is electrically connected to
a battery 23 capable of being charged and discharged, via a first
power drive unit (hereinafter referred to as the "first PDU") 21,
and is capable of supplying and receiving electric energy to and
from the battery 23. The first PDU 21 is formed by an electric
circuit comprising an inverter. As shown in FIG. 2, an ECU 2,
described hereinafter, is electrically connected to the first PDU
21. The ECU 2 controls the first PDU 21 to thereby control electric
power supplied to the first stator 113a, electric power generated
by the first stator 113a, and the rotational speed of the first
rotor 113b.
[0082] Similarly to the first motor 113, the second motor 114 as
well is an AC motor, and includes a second stator 114a and a second
rotor 114b. The second stator 114a and the second rotor 114b are
constructed similarly to the first stator 113a and the first rotor
113b, respectively. Further, the second rotor 114b is integrally
attached to the root portion 111a of the above-described carrier
member 111, and is rotatable together with the carrier member 111.
Furthermore, similarly to the first motor 113, the second motor 114
is capable of converting electric power supplied to the second
stator 114a to motive power and outputting the motive power to the
second rotor 114b, and is capable of converting the motive power
input to the second rotor 114b to electric power and outputting the
electric power to the second stator 114a.
[0083] Further, the second stator 114a is electrically connected to
the battery 23 via a second power drive unit (hereinafter referred
to as the "second PDU") 22, and is capable of supplying and
receiving electric energy to and from the battery 23. Similarly to
the first PDU 21, the second PDU 22 is formed by an electric
circuit comprising an inverter. The ECU 2 is electrically connected
to the second PDU 22. The ECU 2 controls the second PDU 22 to
thereby control electric power supplied to the second stator 114a,
electric power generated by the second stator 114a, and the
rotational speed of the second rotor 114b.
[0084] As described above, in the power transmission system T, the
first pinion gear P1 of each triple pinion gear 112 is connected to
the right output shaft SFR via the first sun gear S1, the rotating
shaft 115, and the carrier CD. The second pinion gear P2 is
connected to the left output shaft SFL via the second sun gear S2.
Further, the third pinion gear P3 is connected to the first motor
113 via the third sun gear S3 and the rotating shaft 116. The
carrier member 111 is connected to the second motor 114.
[0085] Further, as shown in FIG. 2, input to the ECU 2 are a
detection signal indicative of a steering angle .theta. of a
steering wheel (not shown) of the vehicle from a steering angle
sensor 31, a detection signal indicative of a vehicle speed VP from
a vehicle speed sensor 32, and a detection signal indicative of an
operation amount of an accelerator pedal (not shown) of the vehicle
(hereinafter referred to as the "accelerator pedal opening") AP
from an accelerator pedal opening sensor 33. Further, detection
signals indicative of current and voltage values of electric
current flowing into and out of the battery 23 are input from a
current/voltage sensor 34 to the ECU 2. The ECU 2 calculates a
state of charge of the battery 23 based on the detection signals
from the current/voltage sensor 34.
[0086] The ECU 2 is implemented by a microcomputer comprising an
I/O interface, a CPU, a RAM, and a ROM, and controls the first and
second motors 113 and 114 based on the detection signals from the
aforementioned sensors 31 to 34, according to control programs
stored in the ROM. With this control, various operations of the
power transmission system T are performed. Hereafter, a description
will be given of the operations of the power transmission system T
during straight forward traveling and during left and right turning
of the vehicle.
[0087] [During Straight Forward Traveling]
[0088] As is apparent from a relationship of connections between
the above-described elements, such as the engine 3 and the first
and second motors 113 and 114, the engine torque is transmitted to
the first and second motors 113 and 114 via the differential gear
D, the carrier member 111, and the triple pinion gears 112. This
causes the carrier member 111, and the first and second rotors 113b
and 114b to idly rotate. To avoid dragging losses from being caused
by electric power generation by the first and second motors 113 and
114 along with the idle rotation, zero torque control is performed
such that torque of the motors 113 and 114 becomes substantially
equal to 0.
[0089] During the straight forward traveling of the vehicle, the
engine torque is distributed to the left and right output shafts
SFL and SFR via the differential gear D, and is further transmitted
to the left and right drive wheels WFL and WFR. In this case, as
indicated by hatched arrows in FIG. 3, a torque distribution ratio
for distributing the engine torque from the engine 3 to the left
and right output shafts SFL and SFR is 1:1. Further, differently
from during the left and right turning of the vehicle, the carrier
member 111 idly rotates at the same rotational speed as that of the
left and right output shafts SFL and SFR, whereas the triple pinion
gears 112 do not rotate with respect to the carrier member 111, so
that no torque is transmitted between the left and right output
shafts SFL and SFR via the triple pinion gears 112.
[0090] [During Left Turning]
[0091] Power generation control is performed by the first motor
113, and the zero torque control is performed by the second motor
114. As the power generation control is performed by the first
motor 113, a braking force from the first motor 113 acts on the
third sun gear S3. Further, rotational energy transmitted to the
first motor 113 is converted to electric energy by the power
generation control by the first motor 113, and the electric energy
obtained by the conversion is charged into the battery 23. This
increases the rotational speed of the carrier member 111 with
respect to that of the left output shaft SFL, whereby as indicated
by hatched arrows in FIG. 4, part of the torque of the left output
shaft SFL is transmitted to the right output shaft SFR via the
second sun gear S2, the second pinion gear P2, the first pinion
gear P1, the first sun gear S1, the rotating shaft 115, and the
carrier CD. As a consequence, the rotational speed of the right
output shaft SFR (hereinafter referred to as the "right output
shaft rotational speed") NFR is increased with respect to the
rotational speed of the left output shaft SFL (hereinafter referred
to as the "left output shaft rotational speed") NFL.
[0092] During the left turning, when the first motor 113 is
controlled such that the rotational speed of the first rotor 113b
becomes equal to 0, the relationship between the left and right
output shaft rotational speeds NFL and NFR is expressed by the
following equation (1):
NFR/NFL={1-(ZS3/ZP3).times.(ZP1/ZS1)}/{1-(ZS3/ZP3).times.(ZP2/ZS2)}=1.16-
7 (1)
[0093] Further, during the left turning, the degree of increase in
the rotational speed of the carrier member 111 with respect to that
of the left output shaft SFL is controlled by controlling the
braking force from the first motor 113 using electric power
generated by the first motor 113, whereby it is possible to freely
control the torque transmitted from the left output shaft SFL to
the right output shaft SFR.
[0094] [During Right Turning]
[0095] During the right turning, inversely to the case of the
above-described left turning, power generation control is performed
by the second motor 114, and the zero torque control is performed
by the first motor 113. As the power generation control is
performed by the second motor 114, a braking force from the second
motor 114 acts on the carrier member 111. Further, rotational
energy transmitted to the second motor 114 is converted to electric
energy by the power generation control by the second motor 114, and
the electric energy obtained by the conversion is charged into the
battery 23. This reduces the rotational speed of the carrier member
111 with respect to that of the left output shaft SFL, whereby as
indicated by hatched arrows in FIG. 5, part of the torque of the
right output shaft SFR is transmitted to the left output shaft SFL
via the carrier CD, the rotating shaft 115, the first sun gear S1,
the first pinion gear P1, the second pinion gear P2, and second sun
gear S2. As a consequence, the left output shaft rotational speed
NFL is increased with respect to the right output shaft rotational
speed NFR.
[0096] During the right turning, when the second motor 114 is
controlled such that the rotational speed of the second rotor 114b
becomes equal to 0, the relationship between the left and right
output shaft rotational speeds NFL and NFR is expressed by the
following equation (2):
NFL/NFR=(ZP2/ZS2).times.(ZS1/ZP1)=1.143 (2)
[0097] Further, during the right turning, the degree of the
reduction in the rotational speed of the carrier member 111 with
respect to that of the left output shaft SFL is controlled by
controlling the braking force from the second motor 114 using
electric power generated by the second motor 114, whereby it is
possible to freely control the torque transmitted from the right
output shaft SFR to the left output shaft SFL.
[0098] Further, the correspondence between various elements of the
present embodiment and various elements of the present invention is
as follows: The left and right output shafts SFL and SFR in the
present embodiment correspond to one and the other of the two
rotating shafts in the present invention, respectively. Further,
the first motor 113 in the present embodiment corresponds to a
first torque generator in the present invention, and the second
motor 114 in the present embodiment corresponds to a second torque
generator in the present invention. Furthermore, the first and
second motors 113 and 114 in the present embodiment correspond to
rotating electric machines in the present invention.
[0099] As described above, according to the first embodiment, the
triple pinion gears 112 are rotatably supported by the carrier
member 111 which is rotatably disposed around the left output shaft
SFL. Each triple pinion gear 112 comprises the first to third
pinion gears P1 to P3 having pitch circles different from each
other and integrally formed with each other. Further, the first and
second pinion gears P1 and P2 are connected to the right output
shaft SFR and the left output shaft SFL, respectively, and the
third pinion gear P3 and the carrier member 111 are connected to
the first and second motors 113 and 114, respectively. Furthermore,
the battery 23 is connected to the first and second motors 113 and
114. The first and second motors 113 and 114 are capable of
recovering rotational energy as electric energy for
accumulation.
[0100] Further, during the left turning of the vehicle, rotational
energy transmitted to the first motor 113 is recovered by
performing power generation control by the first motor 113, whereby
the rotational speed of the carrier member 111 is increased with
respect to that of the left output shaft SFL. Further, by
controlling the degree of increase in the rotational speed of the
carrier member 111, it is possible to freely control torque
transmitted from the left output shaft SFL to the right output
shaft SFR.
[0101] Furthermore, during the right turning of the vehicle,
rotational energy transmitted to the second motor 114 is recovered
by performing power generation control by the second motor 114,
whereby the rotational speed of the carrier member 111 is reduced
with respect to that of the left output shaft SFL. Further, by
controlling the degree of reduction in the rotational speed of the
carrier member 111, it is possible to freely control torque
transmitted from the right output shaft SFR to the left output
shaft SFL. As described above, distribution of torque to the left
and right output shafts SFL and SFR can be freely controlled.
Hereinafter, control of the distribution of torque to the left and
right output shafts SFL and SFR is referred to as the "torque
distribution control".
[0102] Further, to perform the torque distribution control, the
first and second motors 113 and 114 are used in place of the
above-described conventional speed-increasing and speed-reducing
clutches, and hence during the torque distribution control,
rotational energy transmitted to the first and second motors 113
and 114 can be recovered for reuse, which makes it possible to
suppress loss as a whole. Particularly differently from the case
where the speed-increasing and speed-reducing clutches are wet
friction clutches, the aforementioned zero torque control prevents
occurrence of large dragging losses, which also makes it possible
to suppress loss. In addition to this, it is also possible to
dispense with a hydraulic pump for supplying oil pressure to the
speed-increasing and speed-reducing clutches. Furthermore, it is
also possible to dispense with a spool valve for actuating the
speed-increasing and speed-reducing clutches, a solenoid, a
strainer, and so forth, which makes it possible to downsize the
power transmission system T and enhance mountability thereof.
[0103] Further, during the torque distribution control, when
recovering rotational energy transmitted to the first and second
motors 113 and 114, it is possible to convert the rotational energy
to electric energy using the first and second motors 113 and 114.
Therefore, for example, by supplying the electric energy obtained
by the conversion to a vehicle accessory (not shown), it is
possible to reduce the operating load and operating frequency of a
generator (not shown) for charging the power source of the
accessory.
[0104] Furthermore, during deceleration of the vehicle, the power
generation control can be performed by the first and second motors
113 and 114 by using motive power transmitted from the left and
right front wheels WFL and WFR to the first and second motors 113
and 114 e.g. via the left and right output shafts SFL and SFR and
the differential gear D, whereby it is possible to recover the
traveling energy of the vehicle.
[0105] Next, a power transmission system according to a second
embodiment of the present invention will be described with
reference to FIG. 6. In this power transmission system, differently
from the power transmission system T according to the first
embodiment, the first and second motors 113 and 114 are not
directly connected to the third sun gear S3 and the carrier member
111, respectively, but connected via a reduction gear. In FIG. 6,
the same component elements as those of the first embodiment are
denoted by the same reference numerals. The following description
is mainly given of different points of the power transmission
system from the first embodiment.
[0106] The first rotor 113b is not attached to the rotating shaft
116. A gear 141 and a gear 142 are integrally attached to the first
rotor 113b and the rotating shaft 116, respectively. These gears
141 and 142 are in mesh with each other. Motive power of the first
motor 113 is transmitted to the third sun gear S3 in a state
reduced in speed by the gears 141 and 142. Further, the second
rotor 114b is not attached to the carrier member 111, and a gear
143 and a gear 144 are integrally attached to the second rotor 114b
and the root portion 111a of the carrier member 111, respectively.
These gears 143 and 144 are in mesh with each other. Motive power
of the second motor 114 is transmitted to the carrier member 111 in
a state reduced in speed by the gears 143 and 144.
[0107] As described hereinabove, in the second embodiment, the
first motor 113 is connected to the third sun gear S3 via a
reduction gear comprising the gear 141 and the gear 142, and the
second motor 114 is connected to the carrier member 111 via a
reduction gear comprising the gear 143 and the gear 144. This makes
it possible to transmit torque (braking forces) of the first and
second motors 113 and 114 to the third sun gear S3 and the carrier
member 111 in a an increased state, respectively, so that it is
possible to downsize the first and second motors 113 and 114. In
addition to this, it is possible to obtain the same advantageous
effects as provided by the first embodiment.
[0108] Next, a power transmission system according to a third
embodiment of the present invention will be described with
reference to FIG. 7. In this power transmission system, differently
from the power transmission system according to the second
embodiment, the first and second motors 113 and 114 are connected
to the third sun gear S3 and the carrier member 111, respectively,
not via a reduction gear comprising a pair of gears but via a first
reduction gear RG1 and a second reduction gear RG2 each of a
planetary gear type. In FIG. 7, the same component elements as
those of the first and second embodiments are denoted by the same
reference numerals. The following description is mainly given of
different points of the power transmission system from the first
and second embodiments.
[0109] The first reduction gear RG1 is a planetary gear unit of a
single pinion type, and comprises a first sun gear SR1, a first
ring gear RR1 disposed around an outer periphery of the first sun
gear SR1, a plurality of first pinion gears PR1 in mesh with the
gears SR1 and RR1, and a first carrier CR1 rotatably supporting the
first pinion gears PR1.
[0110] The first sun gear SR1 is integrally attached to a hollow
cylindrical rotating shaft 117. The rotating shaft 117 is rotatably
supported by a bearing (not shown), and the left output shaft SFL
is relatively rotatably disposed inside the rotating shaft 117.
Further, the first rotor 113b is integrally attached not to the
above-described rotating shaft 116 but to the rotating shaft 117,
and is rotatable together with the rotating shaft 117 and the first
sun gear SR1. The first ring gear RR1 is fixed to the casing CA.
The first carrier CR1 is integrally attached to the rotating shaft
116, and is rotatable together with the rotating shaft 116 and the
third sun gear S3. Motive power of the first motor 113 is
transmitted to the third sun gear SR3 in a state reduced in speed
by the first reduction gear RG1 constructed as above.
[0111] The above-mentioned second reduction gear RG2 is a planetary
gear unit of a single pinion type, similarly to the first reduction
gear RG1, and comprises a second sun gear SR2, a second ring gear
RR2 disposed around an outer periphery of the second sun gear SR2,
and second pinion gears PR2 in mesh with the gears SR2 and RR2.
[0112] The second sun gear SR2 is integrally attached to a hollow
cylindrical rotating shaft 118. The rotating shaft 118 is rotatably
supported by a bearing (not shown), and the above-described
rotating shaft 115 and left output shaft SFL are relatively
rotatably disposed inside the rotating shaft 118. Further, the
second rotor 114b is integrally attached not to the carrier member
111 but to the rotating shaft 118, and is rotatable together with
the rotating shaft 118 and the second sun gear SR2. The second ring
gear RR2 is fixed to the casing CA. The second pinion gears PR2 are
equal in number (four, only two of which are shown) to the triple
pinion gears 112, and are rotatably supported on the support shafts
111b of the carrier member 111. Motive power of the second motor
114 is transmitted to the carrier member 111 in a state reduced in
speed by the second reduction gear RG2 constructed as above.
[0113] As described hereinabove, in the third embodiment, the first
motor 113 is connected to the third sun gear S3 via the first
reduction gear RG1, and the second motor 114 is connected to the
carrier member 111 via the second reduction gear RG2. This makes it
possible, similarly to the second embodiment, to transmit torque
(braking forces) of the first and second motors 113 and 114 to the
third sun gear S3 and the carrier member 111 in an increased state,
respectively, so that it is possible to downsize the first and
second motors 113 and 114. In addition to this, it is possible to
obtain the same advantageous effects as provided by the first
embodiment.
[0114] Further, since the carrier member 111 supporting the triple
pinion gears 112 and the second pinion gears PR2 is shared, it is
possible to downsize the power transmission system and enhance
mountability thereof.
[0115] As shown in FIG. 8, the power transmission system according
to the present invention can also be applied to a vehicle VFR of an
FR (front-engine rear-drive) type. In this vehicle VFR, a power
transmission system TA is arranged in a rear part of the vehicle
VFR, and the above-described ring gear (not shown) of the
differential gear D is connected to the transmission 4 via a
propeller shaft PS. Further, the sun gear and the carrier (none of
which are shown) of the differential gear D are connected to left
and right rear wheels WRL and WRR via left and right output shafts
SRL and SRR, respectively. With the above arrangement, engine
torque is transmitted to the left and right rear wheels WRL and WRR
via the transmission 4, the propeller shaft PS, the power
transmission system TA, and the left and right output shafts SRL
and SRR, respectively. In this case as well, it is possible to
obtain the same advantageous effects as provided by the first to
third embodiments.
[0116] Furthermore, as shown in FIG. 9, the power transmission
system according to the present invention can also be applied to an
all-wheel drive vehicle VAW. In this vehicle VAW, the left and
right output shafts SFL and SFR are connected to the engine 3 via a
front differential DF, a center differential DC, and the
transmission 4. Further, a power transmission system TB is arranged
in a rear part of the vehicle VAW, and the ring gear (not shown) of
the differential gear D is connected to the transmission 4 via the
propeller shaft PS and the center differential DC. Further, the sun
gear and the carrier (none of which are shown) of the differential
gear D are connected to the left and right rear wheels WRL and WRR
via the left and right output shafts SRL and SRR, respectively.
[0117] With the above arrangement, engine torque is transmitted to
the center differential DC via the transmission 4, and is
distributed to the front differential DF and the propeller shaft
PS. The torque distributed to the front differential DF is
transmitted to the left and right front wheels WFL and WFR via the
left and right output shafts SFL and SFR, respectively. The torque
distributed to the propeller shaft PS is transmitted to the left
and right rear wheels WRL and WRR via the power transmission system
TB and the left and right output shafts SRL and SRR, respectively.
In this case as well, it is possible to obtain the same
advantageous effects as provided by the first to third
embodiments.
[0118] Note that the present invention is by no means limited to
the first to third embodiments (including the variation) described
above, but can be practiced in various forms. For example, although
in the above-described first to third embodiments, the carrier
member 111 is rotatably disposed around the left output shaft SFL
(SRL), it may be rotatably disposed around the right output shaft
SFR (SRR).
[0119] Further, although in the above-described first to third
embodiments, the power transmission system according to the present
invention is configured such that torque is transmitted between the
left and right output shafts SFL and SFR (SRL and SRR), the power
transmission system may be configured such that torque is
transmitted between the front and rear drive wheels of the
all-wheel drive vehicle. Alternatively, the power transmission
system may be configured such that torque is transmitted between
non-drive wheels which are not driven directly by a motive power
source, such as that of the engine 3.
[0120] Next, a fourth embodiment of the present invention will be
described with reference to FIG. 10. In the figure, the same
component elements as those of the first embodiment are denoted by
the same reference numerals. The following description is mainly
given of different points from the first embodiment. A power plant
1 according to the fourth embodiment drives the left and right
output shafts SRL and SRR of a four-wheel vehicle (not shown), and
is mounted in a rear part of the vehicle. These left and right
output shafts SRL and SRR are arranged coaxially with each other,
and are connected to the left and right rear wheels WRL and WRR,
respectively. Further, an engine (not shown) as a motive power
source is mounted in a front part of the vehicle. The engine is a
gasoline engine, and is connected to left and right front wheels
(not shown) of the vehicle via a transmission (not shown) for
driving the left and right front wheels.
[0121] The power plant 1 includes a gear unit GS, a first rotating
electric machine 11 and a second rotating electric machine 12 as
motive power sources. The gear unit GS transmits torque between the
first and second rotating electric machines 11 and 12, and the left
and right output shafts SRL and SRR, and comprises a carrier member
13, triple pinion gears 14, and the first sun gear S1, the second
sun gear S2, and the third sun gear S3, described in the first
embodiment.
[0122] Similarly to the carrier member 111 described in the first
embodiment, the carrier member 13 comprises an annular plate-shaped
root portion 13a and four support shafts 13b (only two of which are
shown) for supporting the triple pinion gears 14. The carrier
member 13 is rotatably supported by a bearing (not shown), and is
disposed around the left and right output shafts SRL and SRR. Each
support shaft 13b is integrally attached to the root portion 13a,
and extends from the root portion 13a in the axial direction.
Further, the four support shafts 13b are arranged at equally-spaced
intervals in the circumferential direction of the root portion
13a.
[0123] Similarly to the triple pinion gears 112 described in the
first embodiment, the triple pinion gears 14 each comprise the
first pinion gear P1, the second pinion gear P2, and the third
pinion gear P3, which are integrally formed with each other. The
number N of the triple pinion gears 14 is 4 (only two of which are
shown), and each triple pinion gear 14 is rotatably supported on an
associated one of the support shafts 13b. The first to third pinion
gears P1 to P3 are arranged on the same axis parallel to the axis
of the carrier member 13 from the right side in the mentioned
order. Note that the number N of the triple pinion gears 14 and the
number of the support shafts 13b are not limited to 4 but they can
be set as desired. The pitch circle diameters and the number of the
gear teeth of the first to third pinion gears P1 to P3 are set
similarly to the first embodiment.
[0124] Further, the above-described first sun gear S1, second sun
gear S2 and third sun gear S3 are in mesh with the first to third
pinion gears P1, P2 and P3, respectively. The first to third sun
gears S1 to S3 have pitch circle diameters different from each
other. The first sun gear S1 is integrally attached to the right
output shaft SRR, and the second sun gear S2 is integrally attached
to the left output shaft SRL. The third sun gear S3 is integrally
attached to a rotating shaft 15. The rotating shaft 15 is rotatably
supported by a bearing (not shown), and the left output shaft SRL
is relatively rotatably disposed inside the rotating shaft 15. The
first to third sun gear tooth numbers ZS1 to ZS3 (the numbers of
the gear teeth of the first to third sun gears S1 to S3) are set
similarly to the first embodiment.
[0125] Similarly to the first motor 113 described in the first
embodiment, the first rotating electric machine 11 is an AC motor,
and includes a first stator 11a formed e.g. by a plurality of iron
cores and coils, and a first rotor 11b formed e.g. by a plurality
of magnets. The first stator 11a is fixed to the immovable casing
CA. The first rotor 11b is disposed in a manner opposed to the
first stator 11a, and is integrally attached to the above-mentioned
rotating shaft 15 such that it is rotatable together with the
rotating shaft 15 and the third sun gear S3. In the first rotating
electric machine 11, when electric power is supplied to the first
stator 11a, the supplied electric power is converted to motive
power, and is output to the first rotor 11b (powering). Further,
when the motive power is input to the first rotor 11b, this motive
power is converted to electric power, and is output to the first
stator 11a (regeneration).
[0126] Further, the first stator 11a is electrically connected to
the battery 23 via the first PDU 21 described in the first
embodiment, and is capable of supplying and receiving electric
energy to and from the battery 23. The ECU 2 described in the first
embodiment (see FIG. 2) controls the first PDU 21 to thereby
control electric power supplied to the first stator 11a, electric
power generated by the first stator 11a, and the rotational speed
of the first rotor 11b.
[0127] Similarly to the first rotating electric machine 11, the
second rotating electric machine 12 as well is an AC motor, and
includes a second stator 12a and a second rotor 12b. The second
stator 12a and the second rotor 12b are constructed similarly to
the first stator 11a and the first rotor 11b, respectively.
Further, the second rotor 12b is integrally attached to the root
portion 13a of the above-described carrier member 13, and is
rotatable together with the carrier member 13. Furthermore,
similarly to the first rotating electric machine 11, the second
rotating electric machine 12 is capable of converting electric
power supplied to the second stator 12a to motive power and
outputting the motive power to the second rotor 12b, and is capable
of converting the motive power input to the second rotor 12b to
electric power and outputting the electric power to the second
stator 12a.
[0128] Further, the second stator 12a is electrically connected to
the battery 23 via the second PDU 22 described in the first
embodiment, and is capable of supplying and receiving electric
energy to and from the battery 23. The ECU 2 controls the second
PDU 22 to thereby control electric power supplied to the second
stator 12a, electric power generated by the second stator 12a, and
the rotational speed of the second rotor 12b.
[0129] Hereinafter, converting electric power supplied to the first
stator 11a (second stator 12a) to motive power and outputting the
motive power from the first rotor 11b (second rotor 12b) is
referred to as "powering", as deemed appropriate. Further,
generating electric power by the first stator 11a (second stator
12a) using motive power input to the first rotor 11b (second rotor
12b) to thereby convert the motive power to electric power is
referred to as "regeneration", as deemed appropriate.
[0130] In the power plant 1 constructed as above, the first to
third sun gears S1 to S3 are in mesh with the first to third pinion
gears P1 to P3 of the triple pinion gears 14 rotatably supported by
the carrier member 13, respectively, and the first to third pinion
tooth numbers ZP1 to ZP3 and the first to third sun gear tooth
numbers ZS1 to ZS3 are set as described hereinabove, so that the
carrier member 13, and the first to third sun gears S1 to S3 can
transmit motive power therebetween, and the rotational speeds
thereof are in a collinear relationship. Here, the term "collinear
relationship" refers to a relationship in which the rotational
speeds are on the same straight line in a collinear chart. Further,
when the triple pinion gears 14 are rotated in a state in which the
carrier member 13 is fixed, all of the first to third sun gears S1
to S3 rotate in a direction opposite to the direction of rotation
of the triple pinion gears 14. The rotational speed of the third
sun gear S3 becomes higher than that of the second sun gear S2, and
the rotational speed of the second sun gear S2 becomes higher than
that of the first sun gear S1. Therefore, in the collinear chart,
the third to first sun gears S3 to S1 and the carrier member 13 are
sequentially aligned in the mentioned order.
[0131] Further, the first rotor 11b and the third sun gear S3 are
connected to each other via the rotating shaft 15. Therefore, the
rotational speeds of the first rotor 11b and the third sun gear S3
are equal to each other. Furthermore, since the second sun gear S2
is directly connected to the left output shaft SRL, the rotational
speeds of the two S1 and SRL are equal to each other, and since the
first sun gear S1 is directly connected to the right output shaft
SRR, the rotational speeds of S1 and SRR are equal to each other.
Further, since the carrier member 13 and the second rotor 12b are
directly connected to each other, the rotational speeds of 13 and
12b are equal to each other.
[0132] From the above, the relationship between the rotational
speeds of the third to first sun gears S3 to S1, the carrier member
13, the left and right output shafts SRL and SRR, the first and
second rotors 11b and 12b is expressed as in a collinear chart
shown in FIG. 11. As is apparent from FIG. 11, the left and right
output shafts SRL and SRR can be differentially rotated with each
other.
[0133] In FIG. 11, .alpha. and .beta. represent a first lever ratio
and a second lever ratio, and are expressed by the following
equations (3) and (4):
.alpha.={1-(ZP2/ZS2).times.(ZS3/ZP3)}/{(ZP2/ZS2).times.(ZS3/ZP3)-(ZP1/ZS-
1).times.(ZS3/ZP3)} (3)
.beta.=(ZP1.times.ZS2)/(ZS1.times.ZP2-ZP1.times.ZS2) (4)
[0134] The power plant 1 is equipped with a differential limiting
mechanism 16 for limiting a differential rotation between the left
and right output shafts SRL and SRR. The differential limiting
mechanism 16 is formed by a hydraulic friction clutch, and includes
an inner 16a and an outer 16b each having an annular plate shape.
The inner 16a and the outer 16b are arranged coaxially with the
carrier member 13 and the first to third sun gears S1 to S3. The
inner 16a is integrally attached to the above-described rotating
shaft 15, and the outer 16b is integrally attached to the four
support shafts 13b of the carrier member 13. The degree of
engagement of the differential limiting mechanism 16 is controlled
by the ECU 2, whereby the rotating shaft 15 and the carrier member
13, i.e. the third sun gear S3 and the carrier member 13 are
connected to and disconnected from each other.
[0135] Further, the ECU 2 controls the differential limiting
mechanism 16 and the first and second rotating electric machines 11
and 12 based on the detection signals from the aforementioned
sensors 31 to 34, according to control programs stored in the ROM.
With this control, various operations of the power plant 1 are
performed. Hereafter, a description will be given of the operations
of the power plant 1 during straight forward traveling and during
left and right turning of the vehicle.
[0136] [During Straight Forward Traveling]
[0137] During straight and constant-speed traveling or straight and
accelerating traveling of the vehicle, powering is performed by
both the first and second rotating electric machines 11 and 12, and
electric power supplied from the battery 23 to the first and second
stators 11a and 12a is controlled. FIG. 11 shows a rotational speed
relationship and a torque balance relationship between various
types of rotary elements in this case. In the figure, TM1 and TM2
represent output torques generated by the first and second rotors
11b and 12b along with the powering by the first and second
rotating electric machines 11 and 12 (hereinafter referred to as
the "first motor output torque" and the "second motor output
torque"), respectively. Further, RLM1 and RRM1 represent reaction
force torques acting on the left output shaft SRL and the right
output shaft SRR along with the powering by the first rotating
electric machine 11, respectively, and RLM2 and RRM2 represent
reaction force torques acting on the left output shaft SRL and the
right output shaft SRR along with the powering by the second
rotating electric machine 12, respectively.
[0138] In this case, torque transmitted to the left output shaft
SRL (hereinafter referred to as the "left output shaft-transmitted
torque") is expressed by RLM1-RLM2 (RLM1>RLM2), and torque
transmitted to the right output shaft SRR (hereinafter referred to
as the "right output shaft-transmitted torque") is expressed by
RRM2-RRM1 (RRM2>RRM1). The left and right output shafts SRL and
SRR are driven in the direction of normal rotation together with
the left and right rear wheels WRL and WRR. Further, electric power
supplied to the first and second stators 11a and 12a are controlled
such that the left output shaft-transmitted torque and the right
output shaft-transmitted torque become the same demanded torque.
This demanded torque is calculated by searching a predetermined map
(not shown) according to the detected accelerator pedal opening AP.
Furthermore, as an execution condition for executing the
above-described powering by the first and second rotating electric
machines 11 and 12, there is employed e.g. a condition that the
engine is being assisted by the first and second rotating electric
machines 11 and 12 (hereinafter referred to as "during the motor
assist"), or a condition that the vehicle is being driven only by
the first and second rotating electric machines 11 and 12 without
using the engine (hereinafter referred to as "during the EV
traveling") and at the same time a calculated state of charge of
the battery 23 is higher than a lower limit value. In this case,
the fact that the state of charge of the battery 23 is higher than
the lower limit value indicates that the battery 23 is capable of
being discharged.
[0139] Further, during straight forward traveling and decelerating
traveling of the vehicle, regeneration is performed by both the
first and second rotating electric machines 11 and 12, and
regenerated electric power is charged into the battery 23 and is
controlled. FIG. 12 shows a rotational speed relationship and a
torque balance relationship between the various types of rotary
elements in this case. In the figure, TG1 and TG2 represent braking
torques generated by the first and second rotors 11b and 12b along
with the regeneration by the first and second rotating electric
machines 11 and 12 (hereinafter referred to as the "first motor
braking torque" and the "second motor braking torque"),
respectively. Further, RLG1 and RRG1 represent reaction force
torques acting on the left output shaft SRL and the right output
shaft SRR along with the regeneration by the first rotating
electric machine 11, and RLG2 and RRG2 represent reaction force
torques acting on the left output shaft SRL and the right output
shaft SRR along with the regeneration by the second rotating
electric machine 12.
[0140] In this case, the left output shaft-transmitted torque is
expressed by -RLG1+RLG2 (RLG1>RLG2), and the right output
shaft-transmitted torque is expressed by -RRG2+RRG1 (RRG2>RRG1).
The braking torque acts on the left and right output shafts SRL and
SRR, and the vehicle is decelerated. Further, the electric power
regenerated by the first and second rotating electric machines 11
and 12 is controlled such that the same braking torque acts on the
left and right output shafts SRL and SRR. Furthermore, e.g. a
condition that the state of charge of the battery 23 is lower than
an upper limit value is used as an execution condition for
executing the above-described regeneration by the first and second
rotating electric machines 11 and 12. In this case, the fact that
the state of charge of the battery 23 is lower than the upper limit
value indicates that the battery 23 is capable of being
charged.
[0141] [During Right Turning]
[0142] During right turning of the vehicle, when a clockwise yaw
moment for causing the vehicle to perform right turning is
increased, yaw moment-increasing control for right turning is
executed. First yaw moment-increasing control to fourth yaw
moment-increasing control are provided for the yaw
moment-increasing control. Hereinafter, a description will be
sequentially given of the first yaw moment-increasing control to
fourth yaw moment-increasing control. First, during the first yaw
moment-increasing control, powering is performed by both the first
and second rotating electric machines 11 and 12, and the electric
power supplied to the first and second stators 11a and 12a is
controlled such that the first motor output torque TM1 becomes
larger than the second motor output torque TM2.
[0143] With this control, as is apparent from the above-described
torque balance relationship shown in FIG. 11, the left output
shaft-transmitted torque becomes larger than the right output
shaft-transmitted torque, whereby the clockwise yaw moment of the
vehicle is increased. In this case, the electric power supplied to
the first and second stators 11a and 12a is controlled according to
the detected steering angle .theta., vehicle speed VP, and
accelerator pedal opening AP. Note that as an execution condition
for executing the first yaw moment-increasing control, there is
employed e.g. a condition that it is during the motor assist (the
engine is being assisted by the first and second rotating electric
machines 11 and 12) or a condition that it is during the EV
traveling (the vehicle is being driven only by the first and second
rotating electric machines 11 and 12) and at the same time the
state of charge of the battery 23 is higher than the lower limit
value.
[0144] During the second yaw moment-increasing control,
regeneration is performed by both the first and second rotating
electric machines 11 and 12, and the electric power regenerated by
the first and second rotating electric machines 11 and 12 is
controlled such that the second motor braking torque TG2 becomes
larger than the first motor braking torque TG1.
[0145] With this control, as is apparent from the above-described
torque balance relationship shown in FIG. 12, the braking torque
acting on the right output shaft SRR becomes larger than the
braking torque acting on the left output shaft SRL, so that the
clockwise yaw moment of the vehicle is increased. In this case, the
electric power regenerated by the first and second rotating
electric machines 11 and 12 is controlled according to the steering
angle .theta., the vehicle speed VP, and so forth. Note that as an
execution condition for executing the second yaw moment-increasing
control, there is employed e.g. a condition that it is during
deceleration traveling of the vehicle and at the same time the
state of charge of the battery 23 is smaller than the upper limit
value.
[0146] During the third yaw moment-increasing control, powering is
performed by the first rotating electric machine 11, and
regeneration is performed by the second rotating electric machine
12. FIG. 13 shows a rotational speed relationship and a torque
balance relationship between the various types of rotary elements
in this case. As described above with reference to FIG. 11, in FIG.
13, TM1 represents the first motor output torque, and RLM1 and RRM1
represent the reaction force torques acting on the left output
shaft SRL and the right output shaft SRR along with the powering by
the first rotating electric machine 11, respectively. Further, as
described above with reference to FIG. 12, in FIG. 13, TG2
represents the second motor braking torque, and RLG2 and RRG2
represent the reaction force torques acting on the left output
shaft SRL and the right output shaft SRR along with the
regeneration by the second rotating electric machine 12.
[0147] In this case, the left output shaft-transmitted torque is
expressed by RLM1+RLG2, and the right output shaft-transmitted
torque is expressed by -(RRM1+RRG2). As described above, the left
output shaft-transmitted torque is increased, and the braking
torque acts on the right output shaft SRR, so that the clockwise
yaw moment of the vehicle is increased. In this case as well,
electric power supplied to the first stator 11a and electric power
regenerated by the second rotating electric machine 12 are
controlled according to the steering angle .theta., the vehicle
speed VP, and the accelerator pedal opening AP.
[0148] Note that as an execution condition for executing the second
yaw moment-increasing control, there is employed the following
first increasing condition or second increasing condition:
[0149] The first increasing condition: The vehicle is being driven
by the engine, and at the same time the state of charge of the
battery 23 is not lower than an upper limit value.
[0150] The second increasing condition: The vehicle is being driven
by the engine, the state of charge of the battery 23 is lower than
the upper limit value, and at the same time braking torque demanded
of the second rotating electric machine 12 is not smaller than a
predetermined first upper limit torque.
[0151] In this case, when the first increasing condition is
satisfied, i.e. when the state of charge of the battery 23 is not
lower than the upper limit value, the battery 23 cannot be charged,
and hence all the electric power regenerated by the second rotating
electric machine 12 is supplied to the first stator 11a without
being charged into the battery 23. On the other hand, when the
second increasing condition is satisfied, part of the electric
power regenerated by the second rotating electric machine 12 is
charged into the battery 23, and the remainder is supplied to the
first stator 11a. In this case, the first motor output torque TM1
is controlled such that an insufficient amount of the second motor
braking torque TG2 with respect to the demanded braking torque is
compensated for.
[0152] During the fourth yaw moment-increasing control, the zero
torque control is performed on the first rotating electric machine
11, and regeneration is performed by the second rotating electric
machine 12 to change regenerated electric power into the battery
23. The zero torque control prevents dragging losses from being
caused by regeneration by the first rotating electric machine 11.
In this case, only the second motor braking torque TG2 is
generated, so that as is apparent from FIG. 13, the left output
shaft-transmitted torque is represented by RLG2, and the right
output shaft-transmitted torque is represented by -RRG2. As
described above, the left output shaft-transmitted torque is
increased, and the braking torque acts on the right output shaft
SRR, so that the clockwise yaw moment of the vehicle is increased.
In other words, part of the torque of the right output shaft SRR is
transmitted to the left output shaft SRL using the second motor
braking torque TG2 as a reaction force. In this case as well, the
electric power regenerated by the second rotating electric machine
12 is controlled according to the steering angle .theta., the
vehicle speed VP, and the accelerator pedal opening AP. Note that
as an execution condition for executing the fourth yaw
moment-increasing control, there is employed e.g. a condition that
the vehicle is being driven by the engine, the state of charge of
the battery 23 is lower than the upper limit value, and at the same
time the braking torque demanded of the second rotating electric
machine 12 is smaller than the above-mentioned first upper limit
torque.
[0153] During the right turning of the vehicle, when the clockwise
yaw moment for causing the vehicle to perform right turning is
reduced, yaw moment-reducing control for right turning is executed.
First yaw moment-reducing control to fourth yaw moment-reducing
control are provided for the yaw moment-reducing control.
Hereinafter, a description will be sequentially given of the first
yaw moment-increasing control to fourth yaw moment-reducing
control. First, during the first yaw moment-reducing control,
powering is performed by both the first and second rotating
electric machines 11 and 12, and electric power supplied to the
first and second stators 11a and 12a is controlled such that the
second motor output torque TM2 becomes larger than the first motor
output torque TM1.
[0154] With this control, as is apparent from the above-described
torque balance relationship shown in FIG. 11, the right output
shaft-transmitted torque becomes larger than the left output
shaft-transmitted torque, so that the clockwise yaw moment of the
vehicle is reduced. In this case, the electric power supplied to
the first and second stators 11a and 12a is controlled according to
the steering angle .theta., the vehicle speed VP, and the
accelerator pedal opening AP. Note that as an execution condition
for executing the first yaw moment-reducing control, there is
employed e.g. a condition that it is during the motor assist or
during the EV traveling, and at the same time the state of charge
of the battery 23 is higher than the lower limit value.
[0155] During the second yaw moment-reducing control, regeneration
is performed by both the first and second rotating electric
machines 11 and 12, and the electric power regenerated by the first
and second rotating electric machines 11 and 12 is charged into the
battery 23. In this case, the electric power regenerated by the
first and second rotating electric machines 11 and 12 is controlled
such that the first motor braking torque TG1 becomes larger than
the second motor braking torque TG2.
[0156] With this control, as is apparent from the above-described
torque balance relationship shown in FIG. 12, the braking torque
acting on the left output shaft SRL becomes larger than the braking
torque acting on the right output shaft SRR, so that the clockwise
yaw moment of the vehicle is reduced. In this case, the electric
power regenerated by the first and second rotating electric
machines 11 and 12 is controlled according to the steering angle
.theta. and the vehicle speed VP. Note that as an execution
condition for executing the second yaw moment-reducing control,
there is employed e.g. a condition that it is during deceleration
traveling of the vehicle, and at the same time the state of charge
of the battery 23 is lower than the upper limit value are used.
[0157] During the third yaw moment-reducing control, regeneration
is performed by the first rotating electric machine 11, and
powering is performed by the second rotating electric machine 12.
FIG. 14 shows a rotational speed relationship and a torque balance
relationship between the various types of rotary elements in this
case. As described above with reference to FIG. 12, in FIG. 14, TG1
represents the first motor braking torque, and RLG1 and RRG1
represent the reaction force torques acting on the left output
shaft SRL and the right output shaft SRR along with the
regeneration by the first rotating electric machine 11,
respectively. Further, as described above with reference to FIG.
11, in FIG. 14, TM2 represents the second motor output torque, and
RLM2 and RRM2 represent the reaction force torques acting on the
left output shaft SRL and the right output shaft SRR along with the
powering by the second rotating electric machine 12.
[0158] In this case, the left output shaft-transmitted torque is
expressed by -(RLG1+RLM2), and the right output shaft-transmitted
torque is expressed by RRG1+RRM2. As described above, the braking
torque acts on the left output shaft SRL, and the right output
shaft-transmitted torque is increased, so that the clockwise yaw
moment of the vehicle is reduced. In this case as well, electric
power regenerated by the first rotating electric machine 11 and
electric power supplied to the second stator 12a are controlled
according to the steering angle .theta. and the vehicle speed
VP.
[0159] Note that as an execution condition for executing the third
yaw moment-reducing control, there is employed the following first
reducing condition or second reducing condition:
[0160] The first reducing condition: It is during deceleration
traveling of the vehicle, and at the same time the state of charge
of the battery 23 is not lower than the upper limit value.
[0161] The second reducing condition: It is during deceleration
traveling of the vehicle, the state of charge of the battery 23 is
lower than the upper limit value, and at the same time braking
torque demanded of the first rotating electric machine 11 is not
lower than a predetermined second upper limit torque.
[0162] In this case, when the first reducing condition is
satisfied, i.e. when the state of charge of the battery 23 is not
lower than the upper limit value, the battery 23 cannot be charged,
and hence all the electric power regenerated by the first rotating
electric machine 11 is supplied to the second stator 12a without
being charged into the battery 23. On the other hand, when the
second reducing condition is satisfied, part of the electric power
regenerated by the first rotating electric machine 11 is charged
into the battery 23, and the remainder is supplied to the second
stator 12a. In this case, the second motor output torque TM2 is
controlled such that an insufficient amount of the first motor
braking torque TG1 with respect to the demanded braking torque is
compensated for.
[0163] During the fourth yaw moment-reducing control, regeneration
is performed by the first rotating electric machine 11, and the
zero torque control is performed on the second rotating electric
machine 12. In this case, only the first motor braking torque TG1
is generated, so that as is apparent from FIG. 14, the left output
shaft-transmitted torque is represented by -RLG1, and the right
output shaft-transmitted torque is represented by RRG1. As
described above, the braking torque acts on the left output shaft
SRL, and the right output shaft-transmitted torque is increased, so
that the clockwise yaw moment of the vehicle is reduced. In other
words, part of the torque of the left output shaft SRL is
transmitted to the right output shaft SRR using the first motor
braking torque TG1 as a reaction force. In this case as well, the
electric power regenerated by the first rotating electric machine
11 is controlled according to the steering angle .theta. and the
vehicle speed VP. Note that as an execution condition for executing
the fourth yaw moment-reducing control, there is employed e.g. a
condition that it is during deceleration traveling of the vehicle,
the state of charge of the battery 23 is lower than the upper limit
value, and at the same time the braking torque demanded of the
first rotating electric machine 11 is smaller than the
above-mentioned second upper limit torque.
[0164] Note that during the left turning of the vehicle, when a
counterclockwise yaw moment for causing the vehicle to perform left
turning is increased, yaw moment-increasing control for left
turning is executed, whereas when the counterclockwise yaw moment
is reduced, yaw moment-reducing control for left turning is
executed. The above-described yaw moment-increasing control and yaw
moment-reducing control for left turning are executed substantially
similarly to the yaw moment-increasing control and yaw
moment-reducing control for right turning, respectively, and
detailed description thereof is omitted.
[0165] During straight forward traveling and left and right turning
of the vehicle, basically, the above-described differential
limiting mechanism 16 holds the third sun gear S3 and the carrier
member 13 in a disconnected state. With this configuration, as is
apparent from the collinear chart shown in FIG. 11, the third sun
gear S3 and the carrier member 13 are differentially rotatably held
with respect to each other within a range where the third sun gear
S3 and the carrier member 13 satisfy a collinear relationship shown
in the figure, and similarly, the left and right output shafts SRL
and SRR are also differentially rotatably held.
[0166] On the other hand, for example, during rapid turning or
high-speed straight forward traveling of the vehicle, with a view
to enhancing the stability of the behavior of the vehicle, to limit
the differential rotation between the left and right output shafts
SRL and SRR, the differential limiting mechanism 16 is controlled
such that the third sun gear S3 and the carrier member 13 are
connected to each other. As shown in FIG. 11 and the like, the
rotational speeds of the third to first sun gears S3 to S1 and the
carrier member 13 are in the collinear relationship, and hence
reaction force torques, which act on the third sun gear S3 and the
carrier member 13 from the differential limiting mechanism 16 along
with connection by the differential limiting mechanism 16, act such
that the third to first sun gears S3 to S1 and the carrier member
13 are caused to rotate in unison with each other, and act on the
left and right output shafts SRL and SRR such that the differential
rotation therebetween is limited. As a consequence, since the
differential rotation between the left and right output shafts SRL
and SRR is limited, oversteer is suppressed during the rapid
turning of the vehicle, and the straight forward traveling
properties of the behavior of the vehicle are enhanced during the
high-speed straight forward traveling thereof, thereby the
stability of the behavior of the vehicle is increased.
[0167] In this case, as is apparent from the description of the
present invention with reference to FIG. 23, as the reaction force
torques acting on the third sun gear S3 and the carrier member 13
from the differential limiting mechanism 16 are larger, the sum
total of the differential limiting torques, which act on the left
and right output shafts SRL and SRR such that the differential
rotation between the left and right output shafts SRL and SRR is
limited (hereinafter referred to as the "total differential
limiting torque") becomes larger. Therefore, by adjusting the
reaction force torques of the differential limiting mechanism 16
through controlling the degree of engagement of the differential
limiting mechanism 16, it is possible to control the total
differential limiting torque, and hence it is possible to control
the degree of limiting the differential rotation between the left
and right output shafts SRL and SRR.
[0168] Further, the correspondence between various elements of the
fourth embodiment and various elements of the invention is as
follows: The left and right output shafts SRL and SRR in the fourth
embodiment correspond to one and the other of the two rotating
shafts in the present invention, respectively, and the first and
second rotating electric machines 11 and 12 in the fourth
embodiment correspond to the first and second torque generators in
the present invention, respectively. Further, the third to first
sun gears S3 to S1 and the carrier member 13 in the fourth
embodiment correspond to first to fourth elements of the gear unit
in the present invention, respectively. Furthermore, the first and
second motor torques TM1 and TM2 in the fourth embodiment
correspond to positive torques in the present invention, and the
first and second motor braking torques TG1 and TG2 correspond to
negative torques in the present invention.
[0169] As described hereinabove, according to the fourth
embodiment, the triple pinion gears 14 are rotatably supported by
the rotatable carrier member 13, and the rotatable first to third
sun gears S1 to S3 are in mesh with the first to third pinion gears
P1 to P3 which are integrally formed with each other to form the
triple pinion gears 14, respectively. Further, the rotational
speeds of the third to first sun gears S3 to S1 and the carrier
member 13 are in the collinear relationship, and are sequentially
aligned in the collinear chart in the mentioned order (see e.g.
FIG. 11).
[0170] Furthermore, the third sun gear S3 is connected to the first
rotating electric machine 11, and the second and first sun gears S2
and S1 are connected to the left and right output shafts SRL and
SRR, respectively. The carrier member 13 is connected to the second
rotating electric machine 12. From the above, it is possible to
transmit the first and second motor output torques TM1 and TM2, and
the first and second motor braking torques TG1 and TG2 to the left
and right output shafts SRL and SRR via the third to first sun
gears S3 to S1 and the carrier member 13, to thereby properly drive
the left and right output shafts SRL and SRR. In this case, the
rotational speeds of the third to first sun gears S3 to S1 and the
carrier member 13 are in the collinear relationship, so that as
described with reference to FIGS. 11 to 14, by controlling the
first and second motor output torques TM1 and TM2, and the first
and second motor braking torques TG1 and TG2, it is possible to
properly control torque distributed to the left and right output
shafts SRL and SRR.
[0171] Further, differently from the above-described conventional
case, to control the torque distributed to the left and right
output shafts SRL and SRR, instead of the speed-increasing and
speed-reducing clutches formed by wet friction clutches, the first
and second rotating electric machines 11 and 12 are used, so that
occurrence of large dragging losses can be prevented by the
aforementioned zero torque control, and hence it is possible to
suppress loss. In addition to this, it is possible to dispense with
a hydraulic pump for supplying oil pressure to the speed-increasing
and speed-reducing clutches. Furthermore, it is also possible to
dispense with a spool valve for actuating the speed-increasing and
speed-reducing clutches, a solenoid, a strainer, and so forth,
which makes it possible to downsize the power plant 1 and enhance
mountability thereof.
[0172] Furthermore, out of the third to first sun gears S3 to S1
and the carrier member 13, the rotational speeds of which are in
the collinear relationship, the third sun gear S3 and the carrier
member 13 are connected to and disconnected from each other by the
differential limiting mechanism 16. This causes the third to first
sun gears S3 to S1 and the carrier member 13 to rotate in unison
with each other, so that it is possible to limit the differential
rotation between the left output shaft SRL to which the second sun
gear S2 is connected, and the right output shaft SRR to which the
first sun gear S1 is connected, thereby making it possible to
enhance the stability of the behavior of the vehicle. In this case,
it is only required to simply connect the differential limiting
mechanism 16, which makes it possible to easily limit the
differential rotation between the left and right output shafts SRL
and SRR, whereby it is possible to obtain high responsiveness of
the differential limiting mechanism 16.
[0173] Further, out of the third to first sun gears S3 to S1 and
the carrier member 13, the third sun gear S3 and the carrier member
13, which are positioned at opposite ends of the collinear chart,
are connected to each other, so that it is possible to obtain the
largest total differential limiting torque. This makes it possible
to reduce reaction force torque which is required of the
differential limiting mechanism 16 so as to limit the differential
rotation between the left and right output shafts SRL and SRR, and
hence it is possible to downsize the differential limiting
mechanism 16, thereby making it possible to further downsize the
power plant 1 and enhance the mountability thereof.
[0174] Further, to form four rotary elements of which the
rotational speeds are in the collinear relationship, the gear unit
GS is used which comprises the carrier member 13, the triple pinion
gears 14, and the first to third sun gears S1 to S3. For this
reason, to form the above four rotary elements, for example,
compared with a case where the gear unit is constructed by a
combination of two planetary gear units each of a single pinion
type, it is possible to reduce the number of component parts, and
reduce the radial size of the gear unit GS since the gear unit GS
includes no ring gear.
[0175] Furthermore, since the first and second rotating electric
machines 11 and 12 are used, it is possible to construct the power
plant 1 easily and more inexpensively without using a special
device. Further, in the case where distribution of torque to the
left and right output shafts SRL and SRR is controlled as described
above, when the first and second motor braking torques TG1 and TG2
are generated, it is possible to convert motive power to electric
power using the first and second rotating electric machines 11 and
12. Therefore, e.g. by supplying the electric power obtained by the
conversion to a vehicle accessory, it is possible to reduce the
operating load and operating frequency of a generator for charging
the power source of the accessory.
[0176] Next, a power plant 1A according to a fifth embodiment of
the present invention will be described with reference to FIG. 15.
The power plant 1A is distinguished from the fourth embodiment only
in that reduction gears are provided in a power transmission path
between the first rotor 11b and a differential limiting mechanism
41, and the third sun gear S3, and a power transmission path
between the second rotor 12b and the differential limiting
mechanism 41, and the carrier member 13, respectively. In FIG. 15,
the same component elements as those of the fourth embodiment are
denoted by the same reference numerals. The following description
is mainly given of different points from the fourth embodiment.
[0177] The first rotor 11b is not attached to the above-described
rotating shaft 15, but a gear 51 and a gear 52 are integrally
attached to the first rotor 11b and the rotating shaft 15,
respectively. These gears 51 and 52 are in mesh with each other.
The number of the gear teeth of the gear 51 is set to a smaller
value than that of the gear teeth of the gear 52. Motive power of
the first rotating electric machine 11 is transmitted to the third
sun gear S3 in a state reduced in speed by the gears 51 and 52.
Further, the second rotor 12b is not attached to the carrier member
13 but a gear 53 and a gear 54 are integrally attached to the
second rotor 12b and the root portion 13a of the carrier member 13,
respectively. These gears 53 and 54 are in mesh with each other.
The number of the gear teeth of the gear 53 is set to a smaller
value than that of the gear teeth of the gear 54. Motive power of
the second rotating electric machine 12 is transmitted to the
carrier member 13 in a state reduced in speed by the gears 53 and
54. A gear ratio between the above-described gears 51 and 52, and a
gear ratio between the gears 53 and 54 are set to the same
value.
[0178] Similarly to the fourth embodiment, the differential
limiting mechanism 41 is formed by a friction clutch, and includes
an inner 41a and an outer 41b. Differently from the fourth
embodiment, the inner 41a is integrally attached not to the
rotating shaft 15 but to the first rotor 11b, and the outer 41b is
integrally attached not to the four support shafts 13b of the
carrier member 13 but to the second rotor 12b.
[0179] Further, the degree of engagement of the differential
limiting mechanism 41 is controlled by the above-described ECU,
whereby the first and second rotors 11b and 12b are connected to
and disconnected from each other. In this case, as is apparent from
the fact that the first rotor 11b is connected to the third sun
gear S3 via the gear 51, the gear 52, and the rotating shaft 15,
and the fact that the second rotor 12b is connected to the carrier
member 13 via the gear 53 and the gear 54, the third sun gear S3
and the carrier member 13 are connected to and disconnected from
each other by the differential limiting mechanism 41 as the first
and second rotors 11b and 12b are connected to and disconnected
from each other by differential limiting mechanism 41.
[0180] Further, the correspondence between various elements of the
fifth embodiment and various elements of the invention is as
follows: The gears 51 and 52 in the fifth embodiment correspond to
a first power transmission mechanism in the present invention, and
the gears 53 and 54 in the fifth embodiment correspond to a second
power transmission mechanism in the present invention. The other
correspondence is the same as in the fourth embodiment.
[0181] As described above, according to the fifth embodiment, the
first rotating electric machine 11 is connected to the third sun
gear S3 via a reduction gear comprising the gears 51 and 52, and
the second rotating electric machine 12 is connected to the carrier
member 13 via a reduction gear comprising the gears 53 and 54. This
makes it possible to transmit the first and second motor output
torques TM1 and TM2, and the first and second motor braking torques
TG1 and TG2, in increased states, to the third sun gear S3 and the
carrier member 13, respectively, so that it is possible to downsize
the first and second rotating electric machines 11 and 12.
[0182] Further, similarly to the fourth embodiment, e.g. during
rapid turning or high-speed straight forward traveling of the
vehicle, to limit the differential rotation between the left and
right output shafts SRL and SRR, the differential limiting
mechanism 41 is controlled such that the third sun gear S3 and the
carrier member 13 are connected to each other. Accordingly,
reaction force torques from the differential limiting mechanism 41
act such that the third to first sun gears S3 to S1 and the carrier
member 13 are caused to rotate in unison with each other, and act
on the left and right output shafts SRL and SRR such that the
differential rotation therebetween is limited. This makes it
possible to limit the differential rotation between the left and
right output shafts SRL and SRR, and in turn enhance the stability
of the behavior of the vehicle. In this case as well, similarly to
the fourth embodiment, by controlling the degree of engagement of
the differential limiting mechanism 41, it is possible to control
total differential limiting torque (the sum total of differential
limiting torques acting to limit the differential rotation between
the left and right output shafts SRL and SRR), and hence it is
possible to control the degree of control of limiting the
differential rotation between the left and right output shafts SRL
and SRR.
[0183] Further, differently from the fourth embodiment, the
differential limiting mechanism 41 is connected to the third sun
gear S3 via the gears 51 and 52, and is connected to the carrier
member 13 via the gears 53 and 54. As given in the description of
the fourth embodiment, the total differential limiting torque
becomes larger as the reaction force torques acting from the
differential limiting mechanism 41 on the third sun gear S3 and the
carrier member 13 are larger. According to the fifth embodiment,
the reaction force torques from the differential limiting mechanism
41 can be transmitted to the third sun gear S3 and the carrier
member 13, in increased states, by the gears 51 to 54, so that it
is possible to reduce the reaction force torques required of the
differential limiting mechanism 41 so as to limit the differential
rotation between the left and right output shafts SRL and SRR,
whereby it is possible to attain further downsizing of the
differential limiting mechanism 41. In this case, a space necessary
for arranging the gears 51 to 54 is smaller than a space reduced by
downsizing the above-described differential limiting mechanism 41.
Therefore, by downsizing the differential limiting mechanism 41, it
is possible to further downsize the power plant 1A and enhance the
mountability thereof. In addition to this, it is possible to obtain
the same advantageous effects, such as suppression of loss, as
provided by the fourth embodiment.
[0184] Next, a power plant 1B according to a sixth embodiment of
the present invention will be described with reference to FIG. 16.
This power plant 1B is distinguished from the fourth embodiment
only in that the first reduction gear RG1 and the second reduction
gear RG2 described in the third embodiment are provided in a power
transmission path between the first rotor 11b and the third sun
gear S3, and a power transmission path between the second rotor 12b
and the carrier member 13, respectively. In FIG. 16, the same
component elements as those of the third and fourth embodiments are
denoted by the same reference numerals. The following description
is mainly given of different points from the fourth embodiment.
[0185] The first sun gear SR1 of the first reduction gear RG1 is
integrally attached to a hollow cylindrical rotating shaft 17. This
rotating shaft 17 is rotatably supported by a bearing (not shown),
and the left output shaft SRL is relatively rotatably disposed
inside the rotating shaft 17. Further, the first rotor 11b is
integrally attached not to the above-described rotating shaft 15
but to the rotating shaft 17, and is rotatable together with the
rotating shaft 17 and the first sun gear SR1. Further, the first
ring gear RR1 is fixed to the casing CA. The first carrier CR1 is
integrally attached to the above-described rotating shaft 15, and
is rotatable together with the rotating shaft 15 and the third sun
gear S3. The motive power of the first rotating electric machine 11
is transmitted to the third sun gear SR3 in a state reduced in
speed by the first reduction gear RG1 constructed as above.
[0186] The second sun gear SR2 of the above-described second
reduction gear RG2 is integrally attached to a hollow cylindrical
rotating shaft 18. This rotating shaft 18 is rotatably supported by
a bearing (not shown), and the right output shaft SRR is relatively
rotatably disposed inside the rotating shaft 18. Further, the
second rotor 12b is integrally attached not to the carrier member
13 but to the rotating shaft 18, and is rotatable together with the
rotating shaft 18 and the second sun gear SR2. Further, the second
ring gear RR2 is fixed to the casing CA. The second pinion gears
PR2 are equal in number (four, only two of which are shown) to the
triple pinion gears 14, and are rotatably supported on the support
shafts 13b of the carrier member 13. The motive power of the second
rotating electric machine 12 is transmitted to the carrier member
13 in a state reduced in speed by the second reduction gear RG2
constructed as above.
[0187] As described hereinabove, in the sixth embodiment, the first
rotating electric machine 11 is connected to the third sun gear S3
via the first reduction gear RG1, and the second rotating electric
machine 12 is connected to the carrier member 13 via the second
reduction gear RG2. This makes it possible, similarly to the fifth
embodiment, to transmit the first and second motor output torques
TM1 and TM2 and the first and second motor braking torques TG1 and
TG2, in increased states, to the third sun gear S3 and the carrier
member 13, respectively, so that it is possible to downsize the
first and second rotating electric machines 11 and 12. In addition
to this, it is possible to obtain the same advantageous effects as
provided by the fourth embodiment.
[0188] Further, since the carrier member 13 supporting the triple
pinion gears 14 and the second pinion gears PR2 is shared, it is
possible to attain downsizing of the power plant 1B and enhancement
of the mountability thereof.
[0189] Note that in the fourth to sixth embodiments, the vehicle is
constructed such that the left and right front wheels are driven by
the engine, and the left and right rear wheels WRL and WRR (left
and right output shafts SRL and SRR) are driven by the power plant
1, 1A, or 1B, but inversely, the vehicle may be constructed such
that the left and right output shafts connected to the respective
left and right front wheels are driven by the power plant, and the
left and right rear wheels WRL and WRR are driven by the engine.
Further, although the fourth to sixth embodiments are examples in
which the power plants 1, 1A, and 1B according to the present
invention are applied to the vehicle having the engine installed
thereon, the present invention is not limited to this, but it can
be applied to a vehicle with no engine installed thereon.
[0190] Next, a power plant 1C according to a seventh embodiment of
the present invention will be described with reference to FIG. 17.
Differently from the fourth embodiment, this power plant 1C drives
not the left and right output shafts SRL and SRR connected to the
respective left and right rear wheels WRL and WRR but the left and
right output shafts SFL and SFR connected to the respective left
and right front wheels WFL and WFR, and is distinguished from the
fourth embodiment mainly in that the power plant 1C further
includes the engine 3 as a motive power source, the transmission 4,
and the differential gear D, described in the first embodiment, in
addition to the above-described gear unit GS and so forth. In FIG.
17, the same component elements as those of the first and fourth
embodiments are denoted by the same reference numerals. The
following description is mainly given of different points from the
fourth embodiment.
[0191] The engine 3 is a gasoline engine, and is installed in a
front part of a four-wheel vehicle. The transmission 4 is connected
to a crankshaft (not shown) of the engine 3. The transmission 4 is
a stepped automatic transmission, and has operation thereof
controlled by the above-described ECU 2, to thereby transmit the
motive power of the engine 3 to the output shaft 4a in a state
changed in speed.
[0192] The differential gear D, the second rotating electric
machine 12, the gear unit GS, and the first rotating electric
machine 11 are arranged coaxially with the left and right output
shafts SFL and SFR, between the left and right front wheels WFL and
WFR, from the right side in the mentioned order.
[0193] Further, similarly to the first embodiment, the ring gear RD
of the differential gear D is connected to the engine 3 via the
transmission 4. The sun gear SD of the differential gear D is
connected to the second sun gear S2 of the gear unit GS via a
rotating shaft 61 rotatably supported by a bearing (not shown). The
second sun gear S2 is integrally attached to the left output shaft
SFL.
[0194] Further, the carrier CD of the differential gear D has a
right end thereof integrally attached to the right output shaft
SFR, and a left end thereof integrally attached to a right end of a
hollow cylindrical rotating shaft 62. The first sun gear S1 is
integrally attached to a left end of the rotating shaft 62.
Further, the rotating shaft 62 is rotatably supported by a bearing
(not shown), and the above-mentioned rotating shaft 61 is
relatively rotatably disposed inside the rotating shaft 62. As
described above, the carrier CD is provided in a power transmission
path between the first sun gear S1 and the right output shaft
SFR.
[0195] In the differential gear D constructed as above, similarly
to the first embodiment, when torque of the engine 3 is transmitted
to the ring gear RD via the transmission 4, the torque transmitted
to the ring gear RD is distributed to the sun gear SD and the
carrier CD at a torque distribution ratio of 1:1. The torque
distributed to the sun gear SD is transmitted to the left front
wheel WFL via the left output shaft SFL, and the torque distributed
to the carrier CD is transmitted to the right front wheel WFR via
the right output shaft SFR.
[0196] As described above, in the power plant 1C, the second sun
gear S2 and the sun gear SD are connected to each other via the
rotating shaft 61, and the second sun gear S2 is directly connected
to the left output shaft SFL. Therefore, the rotational speeds of
the second sun gear S2, the sun gear SD, and the left output shaft
SFL are equal to each other. Further, the first sun gear S1 and the
carrier CD are connected to each other via the rotating shaft 62,
and the carrier CD is directly connected to the right output shaft
SFR. Therefore, the rotational speeds of the first sun gear S1, the
carrier CD, and the right output shaft SFR are equal to each
other.
[0197] Furthermore, the relationship between the rotational speeds
of the third to first sun gears S3 to S1 of the gear unit GS, the
carrier member 13, and the first and second rotors 11b and 12b is
the same as in the fourth embodiment. Further, as is apparent from
the fact that the differential gear D is a planetary gear unit of a
double pinion type, the sun gear SD, the ring gear RD, and the
carrier CD can be differentially rotated with each other, and they
are in a collinear relationship in which the rotational speeds
thereof are located on the same straight line in a collinear chart
and are arranged in the mentioned order therein.
[0198] From the above, the relationship between the rotational
speeds of various rotary elements of the power plant 1C are
represented e.g. in a collinear chart shown in FIG. 18. As shown in
the figure, five rotary elements the rotational speeds of which are
in a collinear relationship with each other are formed by the sun
gear SD, the ring gear RD, and the carrier CD of the differential
gear D, the third to first sun gears S3 to S1 of the gear unit GS,
and the carrier member 13. Further, as is apparent from FIG. 18,
the left and right output shafts SFL and SFR can be differentially
rotated with each other.
[0199] Furthermore, FIG. 18 shows a rotational speed relationship
and a torque balance relationship between the various types of
rotary elements in the third yaw moment-increasing control for
right turning. In the figure, TE represents torque transmitted from
the engine 3 to the ring gear RD via the transmission 4, and RLE
and RRE represent reaction force torques which act on the left
output shaft SFL and the right output shaft SFR along with
transmission of torque from the engine 3 to the ring gear RD,
respectively. The other parameters (the first motor output torque
TM1, etc.) are the same as in the fourth embodiment. As is apparent
from the fact that the torque transmitted to the ring gear RD is
distributed to the sun gear SD and the carrier CD at the torque
distribution ratio of 1:1 as mentioned hereinabove, the reaction
force torques RLE and RRE are equal to each other.
[0200] In this case, torque transmitted to the left output shaft
SFL is represented by RLE+RLM1+RLG2, and torque transmitted to the
right output shaft SFR is represented by RRE-(RRM1+RRG2). As
described above, the torque transmitted to the left output shaft
SFL (left front wheel WFL) becomes larger than the torque
transmitted to the right output shaft SFR (right front wheel WFR),
whereby the right-turning yaw moment of the vehicle is
increased.
[0201] As is apparent from a comparison between this FIG. 18, and
FIG. 13 which shows the torque balance relationship etc. in the
third yaw moment-increasing control for right turning, described in
the fourth embodiment, an operation in the third yaw
moment-increasing control is distinguished from the fourth
embodiment only in that the engine torque having the speed thereof
changed by the transmission 4 is distributed to the left and right
output shafts SFL and SFR by the differential gear D. The same
applies to various operations performed during straight forward
traveling and in the first yaw moment-increasing control, and hence
description of the operation by the power unit 1C is omitted.
[0202] Further, the correspondence between various elements of the
seventh embodiment and various elements of the invention is as
follows: The left and right output shafts SFL and SFR in the
seventh embodiment correspond to one and the other of the two
rotating shafts in the present invention, respectively, and the sun
gear SD, the carrier CD, and the ring gear RD in the seventh
embodiment correspond to first to third rotating bodies or fifth to
seventh elements of the differential gear in the present invention.
The engine 3 in the seventh embodiment corresponds to the torque
generator in the present invention. The other correspondence is the
same as in the fourth embodiment.
[0203] As described above, according to the seventh embodiment, the
sun gear SD of the differential gear D is connected to the second
sun gear S2, the carrier CD is provided in a power transmission
path between the first sun gear S1 and the right output shaft SFR,
and the ring gear RD is connected to the engine 3. From the above,
not only the first and second motor output torques TM1 and TM2 but
also the engine torque is transmitted to the left and right output
shafts SFL and SFR, and hence it is possible to reduce torque
required of the first and second rotating electric machines 11 and
12, and thereby make it possible to downsize the two 11 and 12. In
addition to this, it is possible to obtain the same advantageous
effects, such as suppression of loss, and enhancement of the
stability of the behavior of the vehicle, as provided by the fourth
embodiment.
[0204] Next, a power plant 1D according to an eighth embodiment of
the present invention will be described with reference to FIG. 19.
This power plant 1D is distinguished from the seventh embodiment
shown in FIG. 17 only in that the reduction gears described in the
fifth embodiment are provided in the power transmission path
between the first rotor 11b and the differential limiting mechanism
41, and the third sun gear S3, and the power transmission path
between the second rotor 12b and the differential limiting
mechanism 41, and the carrier member 13, respectively. In FIG. 19,
the same component elements as those of the fifth and seventh
embodiments are denoted by the same reference numerals.
[0205] With the above arrangement, according to the eighth
embodiment, similarly to the fifth embodiment, the reaction force
torques from the differential limiting mechanism 41, the first and
second motor output torques TM1 and TM2, and the first and second
motor braking torques TG1 and TG2 can be transmitted to the third
sun gear S3 and the carrier member 13, in increased states, via the
above-mentioned reduction gears, i.e. the gears 51 to 54.
Therefore, it is possible to downsize the differential limiting
mechanism 41, and the first and second rotating electric machines
11 and 12, and in turn to attain downsizing of the power plant 1D
and enhancement of the mountability thereof. In addition to this,
it is possible to obtain the same advantageous effects as provided
by the seventh embodiment.
[0206] Note that the correspondence between various elements of the
eighth embodiment and various elements of the invention is the same
as the correspondence between the second and seventh embodiments
and the invention.
[0207] Next, a power plant 1E according to a ninth embodiment of
the present invention will be described with reference to FIG. 20.
This power plant 1E is distinguished from the seventh embodiment
shown in FIG. 17 only in that the first reduction gear RG1 and the
second reduction gear RG2 described in the sixth embodiment are
provided in the power transmission path between the first rotor 11b
and the third sun gear S3, and the power transmission path between
the second rotor 12b and the carrier member 13, respectively. In
FIG. 20, the same component elements as those of the sixth and
seventh embodiments are denoted by the same reference numerals.
[0208] With the above arrangement, according to the ninth
embodiment, similarly to the sixth embodiment, the first and second
motor output torques TM1 and TM2, and the first and second motor
braking torques TG1 and TG2 can be transmitted to the third sun
gear S3 and the carrier member 13, in increased states, via the
first and second reduction gears RG1 and RG2, respectively, whereby
it is possible to downsize the first and second rotating electric
machines 11 and 12. In addition to this, it is possible to obtain
the same advantageous effects as provided by the seventh
embodiment.
[0209] FIG. 21 shows a first variation of the above-described
seventh to ninth embodiments. This first variation is an example in
which the power plant is applied to the vehicle VFR of an FR
(front-engine rear-drive) type. In this vehicle VFR, the
differential gear D, the gear unit GS, the differential limiting
mechanism, and the first and second rotating electric machines 11
and 12 (none of which are shown) are arranged in a rear part of the
vehicle VFR, and the above-described ring gear (not shown) of the
differential gear D is connected to the transmission 4 via the
propeller shaft PS. Further, the relationship of connections
between the left and right output shafts SRL and SRR, the
differential gear D, the gear unit GS, the differential limiting
mechanism, and the first and second rotating electric machines is
distinguished from the seventh to ninth embodiments only in that
the left and right output shafts SFL and SFR on the front side are
replaced by the left and right output shafts SRL and SRR on the
rear side, and the other of the relationship is the same as in the
seventh to ninth embodiments.
[0210] With the above arrangement, the engine torque is transmitted
to the left and right output shafts SRL and SRR via the
transmission 4, propeller shaft PS, and the differential gear D,
and is further transmitted to the left and right rear wheels WRL
and WRR. Further, the first and second motor output torques and the
first and second motor braking torques are transmitted to the left
and right output shafts SRL and SRR via the gear unit GS and the
differential gear D, and is further transmitted to the left and
right rear wheels WRL and WRR. Furthermore, the differential
rotation between the left and right output shafts SRL and SRR is
limited by connection between the third sun gear and the carrier
member by the differential limiting mechanism (none of which are
shown). Therefore, in the first variation as well, it is possible
to obtain the same advantageous effects as provided by the seventh
to ninth embodiments.
[0211] Further, FIG. 22 shows a second variation of the seventh to
ninth embodiments. This second variation is an example in which the
power plant is applied to the all-wheel drive vehicle VAW. In this
vehicle VAW, the front-side left and right output shafts SFL and
SFR are connected to the engine 3 via the front differential DF,
the center differential DC, and the transmission 4. Further, the
differential gear D, the gear unit GS, the differential limiting
mechanism, and the first and second rotating electric machines
(none of which are shown) are arranged in a rear part of the
vehicle VAW, and the ring gear (not shown) of the differential gear
D is connected to the transmission 4 via the propeller shaft PS and
the center differential DC. Further, the relationship of
connections between the left and right output shafts SRL and SRR,
the differential gear D, the gear unit GS, and the first and second
rotating electric machines is the same as in the above-described
first variation.
[0212] With the above arrangement, the engine torque is transmitted
to the center differential DC via the transmission 4, and is
distributed to the front differential DF and the propeller shaft
PS. The torque distributed to the front differential DF is
transmitted to the left and right output shafts SFL and SFR, and is
further transmitted to the left and right front wheels WFL and WFR.
The torque distributed to the propeller shaft PS is transmitted to
the left and right output shafts SRL and SRR via the differential
gear D, and is further transmitted to the left and right rear
wheels WRL and WRR. Further, the first and second motor output
torques, and the first and second motor braking torques are
transmitted to the left and right output shafts SRL and SRR via the
gear unit GS and the differential gear D, and is further
transmitted to the left and right rear wheels WRL and WRR.
Furthermore, the differential rotation between the left and right
output shafts SRL and SRR is limited by connection between the
third sun gear and the carrier member by the differential limiting
mechanism (none of which are shown). Therefore, in the second
variation as well, it is possible to obtain the same advantageous
effects as provided by the seventh to ninth embodiments.
[0213] Note that the vehicles VFR and VAW of the first and second
variations of the seventh to ninth embodiments correspond to a
moving apparatus according to the present invention. Further,
although in the first and second variations, the engine 3 and the
transmission 4 are arranged in the front parts of the vehicles VFP
and VAW, they may be arranged in the rear parts of the
vehicles.
[0214] Note that the present invention is by no means limited to
the fourth to ninth embodiments (including the variations)
described above, but can be practiced in various forms. For
example, although in the above-described fourth to ninth
embodiments, the first sun gear S1 is connected to the right output
shaft SRR (SFR), and the second sun gear S2 is connected to the
left output shaft SRL (SFL), this is not limitative, but inversely,
the first sun gear S1 may be connected to the left output shaft SRL
(SFL), and the second sun gear S2 may be connected to the right
output shaft SRR (SFR). In this case, the carrier CD of the
differential gear D, described in the seventh to ninth embodiments,
is provided in the power transmission path between the first sun
gear S1 and the left output shaft SRL (SFL).
[0215] Furthermore, although in the fourth to ninth embodiments,
the third to first sun gears S3 to S1, and the carrier member 13
are used as the first to fourth elements in the present invention,
other four rotary elements the rotational speeds of which are in a
collinear relationship with each other may be used as the first to
fourth elements. For example, desired two rotary elements of a sun
gear, a carrier, and a ring gear of a planetary gear unit, and
desired two rotary elements of a sun gear, a carrier, and a ring
gear of a planetary gear unit other than the above may be connected
to each other, and four rotary elements formed by the connection
may be used. In this case, the planetary gear units may be of a
single pinion type or of a double pinion type. Alternatively, four
rotary elements of a so-called Ravigneaux type planetary gear unit
(planetary gear units of the single pinion type and the double
pinion type in which a carrier and a ring gear are shared for use)
may be used.
[0216] Alternatively, there may be used four rotary elements
constructed as follows: A double pinion gear formed by
mutually-integrated first and second pinion gears is rotatably
supported by a rotatable carrier member; three rotary elements are
selected from four rotary elements consisting of a first sun gear
and a first ring gear which are rotatable and are in mesh with the
first pinion gear, and a second sun gear and a second ring gear
which are rotatable and are in mesh with the second pinion gear;
and the four rotary elements is formed by adding the
above-mentioned carrier member to the three rotary elements. In
this case, an unselected one of the rotary elements can be omitted.
Further, the first sun gear or the first ring gear may be brought
into mesh with the first pinion gear via another pinion gear
without being brought into direct mesh with the first pinion gear.
The same applies to the second sun gear and the second ring
gear.
[0217] Further, although in the fourth to ninth embodiments, the
first and second torque generators are the first and second
rotating electric machines 11 and 12, they may be replaced by other
suitable devices, such as hydraulic motors, which can generate
positive torque and negative torque. Further, although in the
fourth to ninth embodiments, the differential limiting mechanisms
16 and 41 are formed by hydraulic clutches, they may be formed by
other suitable mechanisms, such as electromagnetic clutches, which
have a function of connecting and disconnecting between the third
sun gear S3 (first element) and the carrier member 13 (fourth
element).
[0218] Furthermore, although in the fourth to ninth embodiments,
the gears 51 and 52 and the gears 53 and 54 are used as the first
power transmission mechanism and the second power transmission
mechanism in the present invention, respectively, there may be used
other suitable mechanisms, such as a power transmission mechanism
formed by a pair of pulleys and a belt extending around the
pulleys, and a power transmission mechanism formed by a pair of
sprockets and a chain extending around the sprockets, which can
transmit reaction forces from the differential limiting mechanisms
in increased states. Further, although in the fourth to ninth
embodiments, the differential gear D, which is a planetary gear
unit of a double pinion type, is used, a suitable differential gear
of any other type may be used which has the first to third rotating
bodies (fifth to seventh elements) which are differentially
rotatable with respect to each other. For example, there may be
used a planetary gear unit of a single pinion type or a
differential gear of the following type: A type which has a pair of
side gears, a plurality of pinion gears in mesh with the side
gears, and a carrier rotatably supporting the pinion gears, and
distributes torque transmitted to the carrier of the pair of side
gears at a distribution ratio of 1:1.
[0219] Further, although in the fourth to ninth embodiments, the
engine (3), which is a gasoline engine, is used as an energy output
device in the present invention, any other suitable device, such as
a diesel engine, an LPG engine, a CNG (Compressed Natural Gas)
engine, an external combustion engine, a rotating electric machine,
or a hydraulic motor, may be used which can generate positive
torque. Further, although in the fourth to ninth embodiments, the
power plants 1, 1A to 1E according to the present invention are
configured to drive the left and right output shafts SRL and SRR
(SFL and SFR), they may be configured to drive front and rear
output shafts connected to front and rear drive wheels of the
vehicle.
[0220] Further, although in the first to ninth embodiments
(including the variations), the first to third pinion gears P1 to
P3 are integrally formed with each other, they may be formed
separately and then be integrally connected to each other.
[0221] Further, although in the first to third embodiments,
electric power generated and recovered by the first and second
motors 113 and 114 is charged (accumulated) in the battery 23, the
electric power may be accumulated in any other electric energy
accumulator, such as a capacitor (electric power storage device).
Alternatively, any other motor than the first and second motors 113
and 114, and a flywheel (kinetic energy storage device) connected
to the other motor may be used to convert the electric power
generated and recovered by the first and second motors 113 and 114
to motive power using the other motor, and accumulate the motive
power obtained by the conversion in the flywheel as kinetic energy.
Furthermore, the electric power generated and recovered by the
first and second motors 113 and 114 may be directly supplied to a
power consuming device (the other motor, etc.) without providing
the electric or motive power energy storage device described above.
Alternatively, a hydraulic pump capable of converting rotational
energy to pressure energy may be used in place of the first and
second motors 113 and 114, and the pressure energy obtained by the
conversion by the hydraulic pump may be accumulated in the
accumulator. The same applies to the fourth to ninth
embodiments.
[0222] Further, although in the first to third embodiments, the
first and second motors 113 and 114, which are AC motors, are used
as the rotating electric machines in the present invention, any
other suitable device, such as a DC motor, may be used which can
perform energy conversion between rotational energy and electric
energy. Furthermore, although in the first to third embodiments,
the battery 23 is shared by the first and second motors 113 and
114, the battery may be provided separately. The same applies to
the fourth to ninth embodiments.
[0223] Further, although the first to ninth embodiments are
examples in which the present invention is applied to a vehicle,
the present invention is not limited to this, but it may be applied
e.g. to boats or aircrafts. It is to be further understood that
various changes and modifications may be made without departing
from the spirit and scope thereof.
INDUSTRIAL APPLICABILITY
[0224] The present invention is capable of suppressing loss, and is
very useful for attaining downsizing of the power transmission
system and enhancement of the mountability thereof.
REFERENCE SIGNS LIST
[0225] T power transmission system (power plant) [0226] SFL left
output shaft (one of two rotating shafts) [0227] SFR right output
shaft (the other of two rotating shafts) [0228] 111 carrier member
[0229] P1 first pinion gear [0230] P2 second pinion gear [0231] P3
third pinion gear [0232] 112 triple pinion gear [0233] 113 first
motor (first torque generator, rotating electric machine) [0234]
114 second motor (second torque generator, rotating electric
machine) [0235] VFR vehicle (moving apparatus) [0236] VAW vehicle
(moving apparatus) [0237] SRL left output shaft (one of two
rotating shafts) [0238] SRR right output shaft (the other of two
rotating shafts) [0239] 1 power plant [0240] 1A power plant [0241]
1B power plant [0242] 1C power plant [0243] 1D power plant [0244]
1E power plant [0245] 3 engine (torque generator) [0246] 11 first
rotating electric machine (first torque generator) [0247] 12 second
rotating electric machine (second torque generator) [0248] GS gear
unit [0249] 13 carrier member (fourth element) [0250] 14 triple
pinion gear [0251] S1 first sun gear (third element) [0252] S2
second sun gear (second element) [0253] S3 third sun gear (first
element) [0254] 16 differential limiting mechanism [0255] 41
differential limiting mechanism [0256] 51 gear (first power
transmission mechanism) [0257] 52 gear (first power transmission
mechanism) [0258] 53 gear (second power transmission mechanism)
[0259] 54 gear (second power transmission mechanism) [0260] D
differential gear [0261] SD sun gear (first rotating body, fifth
element) [0262] CD carrier (second rotating body, sixth element)
[0263] RD ring gear (third rotating body, seventh element) [0264]
TM1 first motor torque (positive torque) [0265] TG1 first motor
braking torque (negative torque) [0266] TM2 second motor torque
(positive torque) [0267] TG2 second motor braking torque (negative
torque)
* * * * *